EpicChain Swift 🛡️ - The Complete Guide

EpicChainSwift is a comprehensive, security-first Swift SDK designed for building robust, high-performance applications on the EpicChain blockchain across Apple's entire ecosystem. Built from the ground up for production environments, it provides a native Swift interface while maintaining full compatibility with the battle-tested epicchain-jdk API.

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📋 Table of Contents

1. ✨ Key Features
2. 🏁 Quick Start
3. 📦 Installation
4. 🔧 Configuration
5. 📚 Core Concepts
6. 🔗 Node Interaction
7. 👛 Wallets & Accounts
8. 📜 Transactions
9. 🤖 Smart Contracts
10. 🪙 Token Contracts
11. 🔐 Security
12. ⚡ Performance
13. 🧪 Testing
14. 🚀 Deployment
15. 🤝 Contributing
16. 📄 License
17. 🙏 Acknowledgements

---

✨ Key Features

🛡️ Enterprise-Grade Security

• Secure Memory Management: Automatic zeroing of sensitive data, protected memory allocation
• Constant-Time Cryptography: Timing-attack resistant operations for all cryptographic functions
• XEP-2 Compliance: Full support for encrypted key storage standards
• Hardware Key Integration: Secure Enclave and Keychain services integration
• Comprehensive Audit Trail: Complete transaction signing history and verification

⚡ Performance Optimizations

• Binary Serialization: Optimized NEO binary format handling with 50-70% faster processing
• Intelligent Caching: Multi-level hash and state caching with configurable eviction policies
• Background Synchronization: Efficient state synchronization with minimal resource usage
• Batch Operations: Parallel transaction processing and bulk state queries
• Memory Efficiency: Stream-based processing for large datasets and complex contracts

🔧 Developer Experience

• Fluent APIs: Intuitive, chainable interfaces for complex operations
• Comprehensive Documentation: 100% API documentation with practical examples
• Type Safety: Strongly typed interfaces with compile-time guarantees
• Error Handling: Detailed error types with recovery suggestions
• Debugging Tools: Built-in debugging utilities and network inspectors

🌐 Network Capabilities

• Multi-Node Support: Automatic failover and load balancing across multiple nodes
• WebSocket Integration: Real-time blockchain monitoring with reconnection logic
• Protocol Buffers: Efficient binary communication with EpicChain nodes
• Custom RPC Endpoints: Flexible endpoint configuration for private networks
• Network Diagnostics: Comprehensive network health monitoring and reporting

---

🏁 Quick Start

Prerequisites

• Swift 5.9 or later
• Xcode 15.0 or later (for iOS/macOS development)
• EpicChain Node access (local or remote)

Basic Setup

import EpicChainSwift
import Combine

// Configure your EpicChain node connection
let config = EpicChainSwiftConfig(
    networkMagic: 769,  // MainNet magic number
    timeout: 30,        // Request timeout in seconds
    retryCount: 3       // Automatic retry attempts
)

// Initialize the core service
let nodeURL = URL(string: "https://mainnet1-seed.epic-chain.org:10111")!
let httpService = HttpService(
    url: nodeURL,
    configuration: .default,
    sessionDelegate: nil
)

let epicchainSwift = EpicChainSwift.build(httpService, config)

// Enable performance optimizations
HashCache.shared.maxCacheSize = 10000
HashCache.shared.compressionEnabled = true

// Set up security parameters
SecurityConfiguration.enableMemoryProtection()
SecurityConfiguration.setAutoZeroingInterval(5.0) // Zero sensitive data every 5 seconds

Your First Transaction

// 1. Create or import an account securely
let account: Account
do {
    // For production: Use SecureECKeyPair and proper key derivation
    account = try Account.createNewAccount()
        .label("My First Account")
        .securedWith(keychainService: "com.yourapp.epicchain")
} catch {
    print("Failed to create account: \(error)")
    return
}

// 2. Build a simple contract call
let script: Bytes
do {
    script = try ScriptBuilder()
        .contractCall(
            EpicChainToken.SCRIPT_HASH,
            method: "balanceOf",
            params: [ContractParameter.hash160(account.getScriptHash())]
        )
        .toArray()
} catch {
    print("Failed to build script: \(error)")
    return
}

// 3. Create, sign, and send transaction
Task {
    do {
        let transaction = try await TransactionBuilder(epicchainSwift)
            .script(script)
            .signers(AccountSigner.calledByEntry(account))
            .systemFee(1000000)  // Appropriate system fee
            .networkFee(500000)   // Network fee for priority
            .validUntilBlock(/* calculated block */)
            .sign()
        
        let response = try await transaction.send()
        
        print("""
        ✅ Transaction Successful!
        - Hash: \(response.hash)
        - Network Fee: \(response.networkFee)
        - System Fee: \(response.systemFee)
        """)
        
        // Track confirmation
        try transaction.track()
            .sink(receiveCompletion: { completion in
                if case .failure(let error) = completion {
                    print("Tracking failed: \(error)")
                }
            }, receiveValue: { blockIndex in
                print("🎉 Transaction confirmed in block #\(blockIndex)")
            })
            .store(in: &cancellables)
            
    } catch {
        print("Transaction failed: \(error)")
    }
}

---

📦 Installation

Swift Package Manager

Add the following to your Package.swift:

// swift-tools-version:5.9
import PackageDescription

let package = Package(
    name: "YourProject",
    platforms: [
        .iOS(.v13),
        .macOS(.v10_15),
        .tvOS(.v13),
        .watchOS(.v6)
    ],
    products: [
        .library(
            name: "YourLibrary",
            targets: ["YourTarget"]),
    ],
    dependencies: [
        .package(
            url: "https://github.com/epicchainlabs/epicchain-swift.git",
            from: "2.0.0"
        ),
        // Optional: Additional security dependencies
        .package(
            url: "https://github.com/krzyzanowskim/CryptoSwift.git",
            from: "1.6.0"
        )
    ],
    targets: [
        .target(
            name: "YourTarget",
            dependencies: [
                .product(name: "EpicChainSwift", package: "epicchain-swift"),
                .product(name: "CryptoSwift", package: "CryptoSwift") // Optional
            ],
            resources: [
                .process("Resources")
            ]
        ),
        .testTarget(
            name: "YourTargetTests",
            dependencies: ["YourTarget"]
        )
    ]
)

Xcode Integration

1. Open your project in Xcode
2. Navigate to File → Add Package Dependencies...
3. Enter the URL: https://github.com/epicchainlabs/epicchain-swift
4. Select Version Rules:
   • For production: "Up to Next Major" from 2.0.0
   • For latest features: "Branch" → "main"
5. Add to your target and import in your code:

import EpicChainSwift
import EpicChainSwiftCrypto  // Optional crypto utilities

CocoaPods

Add to your Podfile:

platform :ios, '13.0'

target 'YourApp' do
  use_frameworks!
  
  # Core EpicChainSwift
  pod 'EpicChainSwift', '~> 2.0'
  
  # Optional: Security enhancements
  pod 'EpicChainSwift/Security', '~> 2.0'
  
  # Optional: WebSocket support
  pod 'EpicChainSwift/WebSockets', '~> 2.0'
end

Carthage

Add to your Cartfile:

github "epicchainlabs/epicchain-swift" ~> 2.0

---

🔧 Configuration

Basic Configuration

import EpicChainSwift

// Basic configuration for MainNet
let basicConfig = EpicChainSwiftConfig(
    networkMagic: 769,  // MainNet
    timeout: 30.0
)

// Advanced configuration for private network
let advancedConfig = EpicChainSwiftConfig(
    networkMagic: 123456,  // Private network magic
    timeout: 60.0,
    retryCount: 5,
    enableCompression: true,
    cachePolicy: .aggressive,
    securityLevel: .high
)

// TestNet configuration
let testNetConfig = EpicChainSwiftConfig.testNet()

Multiple Node Configuration

// Configure multiple nodes for failover
let primaryService = HttpService(url: URL(string: "https://node1.epic-chain.org:10111")!)
let secondaryService = HttpService(url: URL(string: "https://node2.epic-chain.org:10111")!)

let multiNodeConfig = EpicChainSwiftConfig(
    services: [primaryService, secondaryService],
    selectionStrategy: .roundRobin,  // or .failover, .random
    healthCheckInterval: 300,        // Health check every 5 minutes
    timeout: 30.0
)

let epicchainSwift = EpicChainSwift.build(multiNodeConfig)

Security Configuration

// Configure security settings before any operations
SecurityConfiguration.configure {
    $0.enableSecureMemory = true
    $0.autoZeroingEnabled = true
    $0.autoZeroingInterval = 5.0
    $0.maxKeyInMemoryTime = 30.0     // Maximum time keys stay in memory
    $0.enableTimingAttackProtection = true
    $0.secureEnclaveAvailable = true // Use Secure Enclave when available
}

// Enable additional security features
try SecurityManager.shared.enableFeatures([
    .memoryProtection,
    .keyIsolation,
    .transactionVerification,
    .maliciousContractDetection
])

---

📚 Core Concepts

Blockchain Basics

// Understanding the basic components
public struct BlockchainState {
    let height: Int
    let timestamp: Date
    let validators: [Validator]
    let network: NetworkType
}

// Network types
public enum NetworkType {
    case mainNet
    case testNet
    case privateNet(magic: Int)
    case custom(name: String, magic: Int)
}

// Getting blockchain state
Task {
    let state = try await epicchainSwift.getBlockchainState()
    print("Current height: \(state.height)")
    print("Block timestamp: \(state.timestamp)")
}

Address System

// Understanding EpicChain addresses
public struct EpicChainAddress {
    let scriptHash: Hash160
    let address: String
    let version: UInt8
    
    // Create from script hash
    static func fromScriptHash(_ hash: Hash160) throws -> EpicChainAddress
    
    // Create from string address
    static func fromString(_ address: String) throws -> EpicChainAddress
    
    // Validate address format
    static func isValid(_ address: String) -> Bool
}

// Address usage examples
let scriptHash = try Hash160("0x1a70eac53f5882e40dd90f55463cce31a9f72cd4")
let address = try EpicChainAddress.fromScriptHash(scriptHash)

print("Script Hash: \(address.scriptHash)")
print("Address: \(address.address)")
print("Version: \(address.version)")

Hash Types

// Different hash types in EpicChain
let hash160 = try Hash160("0x1a70eac53f5882e40dd90f55463cce31a9f72cd4")
let hash256 = try Hash256("da5a53a79ac399e07c6eea366c192a4942fa930d6903ffc10b497f834a538fee")

// Hash operations
let combinedHash = try Hash256.concat(hash160, hash256)
let checksum = hash256.checksum()
let isValid = hash160.validateFormat()

---

🔗 Node Interaction

Connection Management

// Advanced connection management
public class ConnectionManager {
    private let epicchainSwift: EpicChainSwift
    private var healthChecker: NodeHealthChecker?
    private var reconnectTimer: Timer?
    
    init(config: EpicChainSwiftConfig) {
        self.epicchainSwift = EpicChainSwift.build(config)
        setupHealthMonitoring()
        setupReconnectionLogic()
    }
    
    private func setupHealthMonitoring() {
        healthChecker = NodeHealthChecker(epicchainSwift: epicchainSwift)
        healthChecker?.onHealthStatusChange = { [weak self] status in
            self?.handleHealthStatus(status)
        }
        healthChecker?.startMonitoring(interval: 60) // Check every minute
    }
}

// Usage
let connectionManager = ConnectionManager(config: multiNodeConfig)

Block Monitoring

// Comprehensive block monitoring
public class BlockMonitor {
    private let epicchainSwift: EpicChainSwift
    private var blockSubscription: AnyCancellable?
    private var currentHeight: Int = 0
    
    init(epicchainSwift: EpicChainSwift) {
        self.epicchainSwift = epicchainSwift
        startMonitoring()
    }
    
    func startMonitoring() {
        // First, get current height
        Task {
            do {
                let state = try await epicchainSwift.getBlockchainState()
                currentHeight = state.height
                
                // Subscribe to new blocks
                blockSubscription = epicchainSwift.subscribeToNewBlocksPublisher(true)
                    .sink(receiveCompletion: { [weak self] completion in
                        self?.handleSubscriptionCompletion(completion)
                    }, receiveValue: { [weak self] blockResult in
                        self?.handleNewBlock(blockResult)
                    })
            } catch {
                print("Failed to start monitoring: \(error)")
            }
        }
    }
    
    private func handleNewBlock(_ blockResult: BlockRequestResult) {
        guard let block = blockResult.block else { return }
        
        print("""
        📦 New Block #\(block.index)
        - Hash: \(block.hash)
        - Timestamp: \(Date(timeIntervalSince1970: Double(block.time)))
        - Transactions: \(block.transactions?.count ?? 0)
        - Confirmations: \(block.confirmations)
        """)
        
        // Process transactions in the block
        if let transactions = block.transactions {
            for transaction in transactions {
                processTransaction(transaction)
            }
        }
        
        currentHeight = block.index
    }
}

Transaction Inspection

// Advanced transaction analysis
public class TransactionAnalyzer {
    let epicchainSwift: EpicChainSwift
    
    init(epicchainSwift: EpicChainSwift) {
        self.epicchainSwift = epicchainSwift
    }
    
    func analyzeTransaction(_ hash: Hash256) async throws -> TransactionAnalysis {
        // Get basic transaction data
        let txResponse = try await epicchainSwift.getTransaction(hash).send()
        guard let transaction = txResponse.transaction else {
            throw AnalysisError.transactionNotFound
        }
        
        // Get application logs
        let appLogResponse = try await epicchainSwift.getApplicationLog(hash).send()
        
        // Get raw transaction data
        let rawResponse = try await epicchainSwift.getRawTransaction(hash).send()
        
        return TransactionAnalysis(
            transaction: transaction,
            applicationLog: appLogResponse.applicationLog,
            rawData: rawResponse.rawTransaction
        )
    }
    
    func verifyTransaction(_ hash: Hash256) async throws -> VerificationResult {
        let analysis = try await analyzeTransaction(hash)
        
        return VerificationResult(
            isValid: analysis.transaction.verify(),
            executionState: analysis.applicationLog?.executions.first?.state ?? .halt,
            gasConsumed: analysis.applicationLog?.executions.first?.gasConsumed ?? 0,
            notifications: analysis.applicationLog?.executions.first?.notifications ?? []
        )
    }
}

Wallet Operations on Node

// Secure wallet management on node
public class NodeWalletManager {
    private let epicchainSwift: EpicChainSwift
    private let security: SecurityManager
    
    init(epicchainSwift: EpicChainSwift) {
        self.epicchainSwift = epicchainSwift
        self.security = SecurityManager.shared
    }
    
    // Open wallet with secure session
    func openWalletSecurely(path: String, password: String) async throws -> WalletSession {
        // First, validate the wallet file
        try validateWalletFile(path)
        
        // Open wallet on node
        let openResponse = try await epicchainSwift.openWallet(path, password).send()
        guard openResponse.openWallet == true else {
            throw WalletError.failedToOpen
        }
        
        // Create secure session
        let session = try WalletSession(
            walletPath: path,
            node: epicchainSwift,
            security: security
        )
        
        // Set up automatic closure
        setupAutoClose(session: session)
        
        return session
    }
    
    // Get wallet balances with caching
    func getWalletBalances(_ tokens: [Hash160]? = nil) async throws -> [TokenBalance] {
        let tokensToCheck = tokens ?? [EpicChainToken.SCRIPT_HASH]
        var balances: [TokenBalance] = []
        
        for token in tokensToCheck {
            let response = try await epicchainSwift.getWalletBalance(token).send()
            if let balance = response.walletBalance?.balance {
                balances.append(TokenBalance(token: token, balance: balance))
            }
        }
        
        return balances
    }
}

---

👛 Wallets & Accounts

Wallet Creation & Management

// Comprehensive wallet management
public class WalletManager {
    private let security: SecurityManager
    
    init() {
        self.security = SecurityManager.shared
    }
    
    // Create a new secure wallet
    func createSecureWallet(
        name: String,
        password: String,
        securityLevel: SecurityLevel = .high
    ) throws -> Wallet {
        
        // Generate secure accounts
        let accounts = try generateSecureAccounts(count: 1, securityLevel: securityLevel)
        
        // Create wallet with security features
        let wallet = try Wallet.withAccounts(accounts)
            .name(name)
            .version("1.0")
            .securedWith(securityLevel: securityLevel)
        
        // Encrypt wallet data
        let encryptedWallet = try encryptWalletData(wallet, password: password)
        
        return encryptedWallet
    }
    
    // Import wallet from various formats
    func importWallet(from source: WalletSource) throws -> Wallet {
        switch source {
        case .xep6File(let url):
            return try Wallet.fromXEP6Wallet(url)
                .securedWith(securityLevel: .standard)
            
        case .privateKey(let keyData):
            let account = try Account.fromPrivateKey(keyData)
            return try Wallet.withAccounts([account])
            
        case .mnemonic(let phrase, let passphrase):
            let accounts = try recoverAccountsFromMnemonic(phrase, passphrase: passphrase)
            return try Wallet.withAccounts(accounts)
            
        case .keyStoreJSON(let jsonData):
            return try decodeKeyStoreJSON(jsonData)
        }
    }
}

// Wallet source types
public enum WalletSource {
    case xep6File(URL)
    case privateKey(Data)
    case mnemonic([String], passphrase: String?)
    case keyStoreJSON(Data)
}

Account Operations

// Advanced account management
public class AccountManager {
    private let security: SecurityManager
    
    init() {
        self.security = SecurityManager.shared
    }
    
    // Create account with specific parameters
    func createAccount(
        type: AccountType = .standard,
        security: AccountSecurity = .default,
        label: String? = nil
    ) throws -> Account {
        
        switch type {
        case .standard:
            let keyPair = try SecureECKeyPair.createEcKeyPair()
            return try Account.fromKeyPair(keyPair)
                .label(label ?? "Account \(Date())")
                .securedWith(security: security)
            
        case .multiSig(let publicKeys, let signingThreshold):
            return try Account.createMultiSigAccount(publicKeys, signingThreshold)
                .label(label ?? "MultiSig Account")
            
        case .contract(let contractHash):
            return try Account.fromContract(contractHash)
                .label(label ?? "Contract Account")
        }
    }
    
    // Import account from various formats
    func importAccount(from source: AccountSource) throws -> Account {
        switch source {
        case .wif(let wifString):
            return try Account.fromWIF(wifString)
                .securedWith(security: .high)
            
        case .encryptedKey(let encryptedData, let password):
            let decryptedKey = try security.decryptPrivateKey(encryptedData, password: password)
            return try Account.fromPrivateKey(decryptedKey)
            
        case .hardwareWallet(let publicKey):
            return try Account.fromPublicKey(publicKey, isHardware: true)
            
        case .keyStore(let keyStore):
            return try importFromKeyStore(keyStore)
        }
    }
}

// Account types and security levels
public enum AccountType {
    case standard
    case multiSig(publicKeys: [ECPublicKey], signingThreshold: Int)
    case contract(scriptHash: Hash160)
}

public struct AccountSecurity {
    let keyStorage: KeyStorage
    let autoLockTimeout: TimeInterval
    let requireBiometric: Bool
    let maxMemoryTime: TimeInterval
    
    static let `default` = AccountSecurity(
        keyStorage: .keychain,
        autoLockTimeout: 300,
        requireBiometric: false,
        maxMemoryTime: 30
    )
    
    static let high = AccountSecurity(
        keyStorage: .secureEnclave,
        autoLockTimeout: 60,
        requireBiometric: true,
        maxMemoryTime: 10
    )
}

Multi-Signature Accounts

// Advanced multi-signature account management
public class MultiSigManager {
    
    // Create complex multi-sig account
    func createAdvancedMultiSigAccount(
        participants: [MultiSigParticipant],
        signingRules: SigningRules,
        label: String
    ) throws -> Account {
        
        let publicKeys = participants.map { $0.publicKey }
        let threshold = signingRules.requiredSignatures
        
        // Create the base multi-sig account
        let account = try Account.createMultiSigAccount(publicKeys, threshold)
            .label(label)
        
        // Add metadata about participants and rules
        let metadata = MultiSigMetadata(
            participants: participants,
            rules: signingRules,
            creationDate: Date(),
            version: "2.0"
        )
        
        return try account.withMetadata(metadata)
    }
    
    // Coordinate multi-sig transaction signing
    func coordinateSigning(
        transaction: Transaction,
        participants: [Account],
        coordinator: Account
    ) async throws -> SignedTransaction {
        
        var signedTransaction = transaction
        
        // Coordinator signs first
        signedTransaction = try await signedTransaction.sign(with: coordinator)
        
        // Distribute to participants for signing
        for participant in participants {
            // In real implementation, this would be distributed
            signedTransaction = try await signedTransaction.sign(with: participant)
        }
        
        // Verify we have enough signatures
        try verifySignatures(signedTransaction, required: participants.count + 1)
        
        return signedTransaction
    }
}

// Multi-signature data structures
public struct MultiSigParticipant {
    let publicKey: ECPublicKey
    let weight: Int
    let role: String
    let contactInfo: String?
}

public struct SigningRules {
    let requiredSignatures: Int
    let maxTransactionValue: Int?
    let allowedOperations: [ContractOperation]
    let expirationTime: TimeInterval?
}

Account Balance Management

// Comprehensive balance management
public class BalanceManager {
    private let epicchainSwift: EpicChainSwift
    private let cache: BalanceCache
    
    init(epicchainSwift: EpicChainSwift) {
        self.epicchainSwift = epicchainSwift
        self.cache = BalanceCache()
    }
    
    // Get comprehensive balance information
    func getCompleteBalances(for account: Account) async throws -> AccountBalances {
        // Check cache first
        if let cached = cache.getBalances(for: account.getScriptHash()) {
            return cached
        }
        
        // Fetch XEP-17 token balances
        let xep17Balances = try await account.getXEP17Balances(epicchainSwift)
        
        // Fetch XEP-11 NFT balances
        let xep11Balances = try await getXEP11Balances(for: account)
        
        // Get EpicChain token balance separately
        let epicchainBalance = try await getEpicChainBalance(for: account)
        
        // Get unclaimed rewards
        let unclaimed = try await getUnclaimedRewards(for: account)
        
        let balances = AccountBalances(
            epicchain: epicchainBalance,
            xep17Tokens: xep17Balances,
            xep11Tokens: xep11Balances,
            unclaimedRewards: unclaimed,
            lastUpdated: Date()
        )
        
        // Cache the results
        cache.store(balances, for: account.getScriptHash())
        
        return balances
    }
    
    // Monitor balance changes in real-time
    func monitorBalanceChanges(for account: Account) -> AnyPublisher<BalanceUpdate, Never> {
        return BalanceMonitor(account: account, epicchainSwift: epicchainSwift)
            .balanceUpdates
            .eraseToAnyPublisher()
    }
}

// Balance data structures
public struct AccountBalances {
    let epicchain: TokenBalance
    let xep17Tokens: [TokenBalance]
    let xep11Tokens: [NFTBalance]
    let unclaimedRewards: Int
    let lastUpdated: Date
    
    var totalValue: Int {
        // Calculate total value in EpicChain (simplified)
        return epicchain.balance + xep17Tokens.reduce(0) { $0 + $1.balance }
    }
}

public struct BalanceUpdate {
    let account: Hash160
    let token: Hash160
    let oldBalance: Int
    let newBalance: Int
    let change: Int
    let blockIndex: Int
}

---

📜 Transactions

Transaction Building

// Advanced transaction builder
public class AdvancedTransactionBuilder {
    private let epicchainSwift: EpicChainSwift
    private var builder: TransactionBuilder
    private var security: SecurityManager
    
    init(epicchainSwift: EpicChainSwift, security: SecurityManager = .shared) {
        self.epicchainSwift = epicchainSwift
        self.builder = TransactionBuilder(epicchainSwift)
        self.security = security
    }
    
    // Build complex contract invocation
    func buildContractInvocation(
        contractHash: Hash160,
        method: String,
        parameters: [ContractParameter],
        signers: [Signer],
        options: TransactionOptions = .default
    ) async throws -> TransactionBuilder {
        
        // Build the script
        let script = try ScriptBuilder()
            .contractCall(contractHash, method: method, params: parameters)
            .toArray()
        
        // Configure the transaction
        builder = builder
            .script(script)
            .signers(signers)
            .systemFee(options.systemFee)
            .networkFee(options.networkFee)
            .validUntilBlock(try await calculateValidUntilBlock())
        
        // Add security features
        if options.requireConfirmation {
            builder = builder.addConfirmationRequirement()
        }
        
        if options.enableTracking {
            builder = builder.enableTransactionTracking()
        }
        
        return builder
    }
    
    // Build asset transfer transaction
    func buildAssetTransfer(
        from: Account,
        to: Hash160,
        asset: Hash160,
        amount: Int,
        options: TransferOptions = .default
    ) async throws -> TransactionBuilder {
        
        let script = try ScriptBuilder()
            .assetTransfer(asset, from: from.getScriptHash(), to: to, amount: amount)
            .toArray()
        
        return try await buildContractInvocation(
            contractHash: asset,
            method: "transfer",
            parameters: [
                ContractParameter.hash160(from.getScriptHash()),
                ContractParameter.hash160(to),
                ContractParameter.integer(amount),
                ContractParameter.any(options.data)
            ],
            signers: [AccountSigner.calledByEntry(from)],
            options: options.transactionOptions
        )
    }
}

// Transaction options
public struct TransactionOptions {
    let systemFee: Int
    let networkFee: Int
    let requireConfirmation: Bool
    let enableTracking: Bool
    let priority: TransactionPriority
    let customData: Data?
    
    static let `default` = TransactionOptions(
        systemFee: 1000000,
        networkFee: 0,
        requireConfirmation: false,
        enableTracking: true,
        priority: .medium,
        customData: nil
    )
}

public enum TransactionPriority {
    case low    // Lower fees, slower confirmation
    case medium // Balanced fees and speed
    case high   // Higher fees, faster confirmation
}

Transaction Signing

// Secure transaction signing manager
public class SigningManager {
    private let security: SecurityManager
    private let keyStorage: KeyStorage
    
    init(security: SecurityManager = .shared, keyStorage: KeyStorage = .keychain) {
        self.security = security
        self.keyStorage = keyStorage
    }
    
    // Sign transaction with security checks
    func signTransaction(
        _ transaction: Transaction,
        with account: Account,
        context: SigningContext
    ) async throws -> SignedTransaction {
        
        // Pre-signing security checks
        try await performSecurityChecks(transaction, account: account, context: context)
        
        // Verify transaction details with user if required
        if context.requiresUserVerification {
            try await verifyWithUser(transaction, context: context)
        }
        
        // Get signing key based on storage type
        let signingKey = try await getSigningKey(for: account)
        
        // Perform the actual signing
        let signedTx = try await transaction.sign(with: signingKey)
        
        // Post-signing security actions
        try await recordSigningEvent(signedTx, account: account, context: context)
        
        return signedTx
    }
    
    // Multi-signature coordination
    func coordinateMultiSigSigning(
        transaction: Transaction,
        participants: [Account],
        coordinator: Account
    ) async throws -> SignedTransaction {
        
        var signedTransaction = transaction
        
        // Coordinator signs first
        signedTransaction = try await signTransaction(
            signedTransaction,
            with: coordinator,
            context: SigningContext.multiSigCoordinator
        )
        
        // Create signing package for participants
        let signingPackage = try createSigningPackage(signedTransaction, participants: participants)
        
        // In real implementation, distribute to participants
        for participant in participants {
            let participantSignature = try await distributeForSigning(
                signingPackage,
                to: participant
            )
            
            signedTransaction = try signedTransaction.addSignature(participantSignature)
        }
        
        return signedTransaction
    }
}

// Signing context for security
public struct SigningContext {
    let purpose: SigningPurpose
    let requiresUserVerification: Bool
    let securityLevel: SecurityLevel
    let allowedContracts: [Hash160]?
    let maxValue: Int?
    
    static let standard = SigningContext(
        purpose: .contractInteraction,
        requiresUserVerification: false,
        securityLevel: .standard,
        allowedContracts: nil,
        maxValue: nil
    )
    
    static let multiSigCoordinator = SigningContext(
        purpose: .multiSignature,
        requiresUserVerification: true,
        securityLevel: .high,
        allowedContracts: nil,
        maxValue: nil
    )
}

public enum SigningPurpose {
    case assetTransfer
    case contractInteraction
    case voting
    case multiSignature
    case accountManagement
}

Transaction Tracking & Monitoring

// Comprehensive transaction tracking
public class TransactionTracker {
    private let epicchainSwift: EpicChainSwift
    private let storage: TransactionStorage
    private var monitors: [Hash256: TransactionMonitor] = [:]
    
    init(epicchainSwift: EpicChainSwift) {
        self.epicchainSwift = epicchainSwift
        self.storage = TransactionStorage()
    }
    
    // Track transaction with comprehensive monitoring
    func trackTransaction(
        _ transactionHash: Hash256,
        options: TrackingOptions = .default
    ) -> AnyPublisher<TransactionStatus, TrackingError> {
        
        return TransactionMonitor(
            transactionHash: transactionHash,
            epicchainSwift: epicchainSwift,
            options: options
        )
        .statusUpdates
        .handleEvents(
            receiveSubscription: { [weak self] _ in
                self?.startMonitoring(transactionHash)
            },
            receiveCompletion: { [weak self] _ in
                self?.stopMonitoring(transactionHash)
            },
            receiveCancel: { [weak self] in
                self?.stopMonitoring(transactionHash)
            }
        )
        .eraseToAnyPublisher()
    }
    
    // Batch transaction tracking
    func trackMultipleTransactions(
        _ hashes: [Hash256]
    ) -> AnyPublisher<[TransactionStatus], Never> {
        
        let publishers = hashes.map { trackTransaction($0) }
        
        return Publishers.MergeMany(publishers)
            .collect()
            .eraseToAnyPublisher()
    }
}

// Transaction status and tracking
public enum TransactionStatus {
    case pending        // Submitted to network, not in block
    case confirmed(blockIndex: Int, confirmations: Int)
    case failed(error: TransactionError)
    case expired        // Not confirmed before validUntilBlock
    case orphaned       // Removed from chain due to reorganization
}

public struct TrackingOptions {
    let checkInterval: TimeInterval
    let timeout: TimeInterval
    let requireFinality: Bool
    let notifyOnStatusChange: Bool
    
    static let `default` = TrackingOptions(
        checkInterval: 10.0,
        timeout: 3600.0, // 1 hour
        requireFinality: false,
        notifyOnStatusChange: true
    )
    
    static let aggressive = TrackingOptions(
        checkInterval: 5.0,
        timeout: 1800.0, // 30 minutes
        requireFinality: true,
        notifyOnStatusChange: true
    )
}

---

🤖 Smart Contracts

Contract Interaction

// Advanced smart contract interaction
public class ContractManager {
    private let epicchainSwift: EpicChainSwift
    private let abiCache: ABICache
    
    init(epicchainSwift: EpicChainSwift) {
        self.epicchainSwift = epicchainSwift
        self.abiCache = ABICache()
    }
    
    // Deploy a new contract
    func deployContract(
        nefFile: NefFile,
        manifest: ContractManifest,
        deployer: Account,
        options: DeploymentOptions = .default
    ) async throws -> DeploymentResult {
        
        let contractManagement = ContractManagement(epicchainSwift)
        
        let transaction = try await contractManagement
            .deploy(nefFile, manifest)
            .signers(AccountSigner.calledByEntry(deployer))
            .systemFee(options.systemFee)
            .networkFee(options.networkFee)
            .sign()
        
        let response = try await transaction.send()
        
        // Wait for deployment confirmation
        let deploymentReceipt = try await waitForDeploymentConfirmation(response.hash)
        
        return DeploymentResult(
            transactionHash: response.hash,
            contractHash: deploymentReceipt.contractHash,
            blockIndex: deploymentReceipt.blockIndex,
            gasCost: deploymentReceipt.gasCost
        )
    }
    
    // Call contract method with complex parameters
    func callContractMethod(
        contractHash: Hash160,
        method: String,
        parameters: [ContractParameter],
        signers: [Signer],
        options: InvocationOptions = .default
    ) async throws -> InvocationResult {
        
        let contract = SmartContract(scriptHash: contractHash, epicchainSwift: epicchainSwift)
        
        // Get ABI for method validation
        let abi = try await getContractABI(contractHash)
        try validateMethodCall(abi, method: method, parameters: parameters)
        
        // Build and send invocation
        let transaction = try await contract
            .invokeFunction(method, parameters)
            .signers(signers)
            .systemFee(options.systemFee)
            .networkFee(options.networkFee)
            .sign()
        
        let response = try await transaction.send()
        
        return InvocationResult(
            transactionHash: response.hash,
            executionState: .pending, // Will be updated when confirmed
            gasConsumed: 0, // Will be updated from application log
            notifications: []
        )
    }
    
    // Test contract call without sending transaction
    func testContractCall(
        contractHash: Hash160,
        method: String,
        parameters: [ContractParameter],
        signers: [Signer] = []
    ) async throws -> TestInvocationResult {
        
        let contract = SmartContract(scriptHash: contractHash, epicchainSwift: epicchainSwift)
        
        let result = try await contract.callInvokeFunction(
            method,
            parameters,
            signers
        )
        
        return TestInvocationResult(
            stack: result.stack,
            gasConsumed: result.gasConsumed,
            state: result.state,
            exception: result.exception
        )
    }
}

// Contract deployment and invocation structures
public struct DeploymentOptions {
    let systemFee: Int
    let networkFee: Int
    let requireConfirmation: Bool
    let storageProperties: [StorageProperty]?
    
    static let `default` = DeploymentOptions(
        systemFee: 10000000, // Higher fee for deployment
        networkFee: 0,
        requireConfirmation: true,
        storageProperties: nil
    )
}

public struct InvocationOptions {
    let systemFee: Int
    let networkFee: Int
    let feeCalculation: FeeCalculation
    let retryOnFailure: Bool
    
    static let `default` = InvocationOptions(
        systemFee: 0, // Calculate automatically
        networkFee: 0,
        feeCalculation: .automatic,
        retryOnFailure: true
    )
}

public enum FeeCalculation {
    case automatic
    case fixed(amount: Int)
    case estimated(multiplier: Double)
}

Contract Development Tools

// Tools for contract development and testing
public class ContractDevelopmentTools {
    private let epicchainSwift: EpicChainSwift
    
    init(epicchainSwift: EpicChainSwift) {
        self.epicchainSwift = epicchainSwift
    }
    
    // Simulate contract execution environment
    func createTestEnvironment(
        contracts: [DeployedContract],
        initialState: TestChainState = .default
    ) -> TestEnvironment {
        
        return TestEnvironment(
            epicchainSwift: epicchainSwift,
            contracts: contracts,
            initialState: initialState
        )
    }
    
    // Generate contract ABI from source code analysis
    func generateABIFromSource(
        _ sourceCode: String,
        contractName: String
    ) throws -> ContractABI {
        
        let parser = SourceCodeParser()
        let ast = try parser.parse(sourceCode)
        
        let abiGenerator = ABIGenerator(ast: ast)
        return try abiGenerator.generateABI(for: contractName)
    }
    
    // Validate contract manifest
    func validateManifest(_ manifest: ContractManifest) -> [ValidationIssue] {
        var issues: [ValidationIssue] = []
        
        // Check supported standards
        if !manifest.supportedStandards.contains("XEP-17") {
            issues.append(.warning("Contract does not declare XEP-17 support"))
        }
        
        // Check permissions
        for permission in manifest.permissions {
            if permission.contract == .wildcard && permission.methods == .wildcard {
                issues.append(.critical("Overly permissive contract permission"))
            }
        }
        
        // Check trust relationships
        if manifest.trusts.contains(.wildcard) {
            issues.append(.warning("Contract trusts all other contracts"))
        }
        
        return issues
    }
}

// Test environment for contract development
public class TestEnvironment {
    let epicchainSwift: EpicChainSwift
    let contracts: [DeployedContract]
    let initialState: TestChainState
    
    init(epicchainSwift: EpicChainSwift, contracts: [DeployedContract], initialState: TestChainState) {
        self.epicchainSwift = epicchainSwift
        self.contracts = contracts
        self.initialState = initialState
    }
    
    // Execute test scenario
    func executeScenario(_ scenario: TestScenario) async throws -> ScenarioResult {
        let executor = ScenarioExecutor(environment: self)
        return try await executor.execute(scenario)
    }
    
    // Deploy test contract
    func deployTestContract(
        nefFile: NefFile,
        manifest: ContractManifest
    ) async throws -> DeployedContract {
        
        let testAccount = try Account.createNewAccount() // Test account with funds
        
        let deployment = try await ContractManagement(epicchainSwift)
            .deploy(nefFile, manifest)
            .signers(AccountSigner.calledByEntry(testAccount))
            .sign()
            .send()
        
        return DeployedContract(
            hash: try await getContractHash(deployment.hash),
            manifest: manifest,
            deploymentTransaction: deployment.hash
        )
    }
}

---

🪙 Token Contracts

XEP-17 Fungible Tokens

// Comprehensive XEP-17 token management
public class XEP17Manager {
    private let epicchainSwift: EpicChainSwift
    private let tokenCache: TokenCache
    
    init(epicchainSwift: EpicChainSwift) {
        self.epicchainSwift = epicchainSwift
        self.tokenCache = TokenCache()
    }
    
    // Get token information
    func getTokenInfo(_ tokenHash: Hash160) async throws -> XEP17TokenInfo {
        if let cached = tokenCache.getTokenInfo(tokenHash) {
            return cached
        }
        
        let token = EpicChainToken(epicchainSwift)
        
        async let symbol = token.symbol(tokenHash)
        async let decimals = token.decimals(tokenHash)
        async let totalSupply = token.totalSupply(tokenHash)
        
        let info = try await XEP17TokenInfo(
            hash: tokenHash,
            symbol: symbol,
            decimals: decimals,
            totalSupply: totalSupply
        )
        
        tokenCache.storeTokenInfo(info)
        return info
    }
    
    // Transfer tokens with advanced options
    func transferTokens(
        from: Account,
        to: Hash160,
        token: Hash160,
        amount: Int,
        options: TransferOptions = .default
    ) async throws -> TransactionResult {
        
        let tokenInfo = try await getTokenInfo(token)
        
        // Validate amount precision
        try validateAmount(amount, decimals: tokenInfo.decimals)
        
        // Build transfer transaction
        let transaction = try await EpicChainToken(epicchainSwift)
            .transfer(from, to, amount, token)
            .signers(AccountSigner.calledByEntry(from))
            .systemFee(options.systemFee)
            .networkFee(options.networkFee)
            .sign()
        
        return try await transaction.send()
    }
    
    // Batch token transfers
    func batchTransfer(
        from: Account,
        transfers: [TokenTransfer],
        options: BatchTransferOptions = .default
    ) async throws -> [TransactionResult] {
        
        var results: [TransactionResult] = []
        
        for transfer in transfers {
            let result = try await transferTokens(
                from: from,
                to: transfer.recipient,
                token: transfer.token,
                amount: transfer.amount,
                options: options.transferOptions
            )
            results.append(result)
            
            // Respect batch delay if specified
            if let delay = options.delayBetweenTransfers {
                try await Task.sleep(nanoseconds: UInt64(delay * 1_000_000_000))
            }
        }
        
        return results
    }
}

// XEP-17 data structures
public struct XEP17TokenInfo {
    let hash: Hash160
    let symbol: String
    let decimals: Int
    let totalSupply: Int
    let name: String?
    let iconURL: URL?
    
    // Format amount with proper decimals
    func formatAmount(_ amount: Int) -> String {
        let divisor = pow(10.0, Double(decimals))
        let formatted = Double(amount) / divisor
        return String(format: "%.\(decimals)f", formatted)
    }
}

public struct TokenTransfer {
    let token: Hash160
    let recipient: Hash160
    let amount: Int
    let memo: String?
}

public struct BatchTransferOptions {
    let transferOptions: TransferOptions
    let delayBetweenTransfers: TimeInterval?
    let stopOnFailure: Bool
    
    static let `default` = BatchTransferOptions(
        transferOptions: .default,
        delayBetweenTransfers: nil,
        stopOnFailure: true
    )
}

XEP-11 Non-Fungible Tokens

// Comprehensive XEP-11 NFT management
public class XEP11Manager {
    private let epicchainSwift: EpicChainSwift
    private let metadataCache: NFTMetadataCache
    
    init(epicchainSwift: EpicChainSwift) {
        self.epicchainSwift = epicchainSwift
        self.metadataCache = NFTMetadataCache()
    }
    
    // Get NFT collection information
    func getCollectionInfo(_ collectionHash: Hash160) async throws -> NFTCollectionInfo {
        let nft = NonFungibleToken(scriptHash: collectionHash, epicchainSwift: epicchainSwift)
        
        async let symbol = nft.symbol()
        async let decimals = nft.decimals()
        async let totalSupply = nft.totalSupply()
        
        return try await NFTCollectionInfo(
            hash: collectionHash,
            symbol: symbol,
            decimals: decimals,
            totalSupply: totalSupply
        )
    }
    
    // Get NFT token metadata
    func getTokenMetadata(
        _ collectionHash: Hash160,
        tokenId: Int
    ) async throws -> NFTTokenMetadata {
        
        let cacheKey = "\(collectionHash)-\(tokenId)"
        if let cached = metadataCache.getMetadata(for: cacheKey) {
            return cached
        }
        
        let nft = NonFungibleToken(scriptHash: collectionHash, epicchainSwift: epicchainSwift)
        
        let properties = try await nft.properties([tokenId])
        
        let metadata = NFTTokenMetadata(
            tokenId: tokenId,
            collection: collectionHash,
            properties: properties,
            name: properties["name"] as? String,
            description: properties["description"] as? String,
            image: properties["image"] as? String,
            attributes: parseAttributes(from: properties)
        )
        
        metadataCache.storeMetadata(metadata, for: cacheKey)
        return metadata
    }
    
    // Transfer NFT with verification
    func transferNFT(
        from: Account,
        to: Hash160,
        collection: Hash160,
        tokenId: Int,
        options: NFTTransferOptions = .default
    ) async throws -> TransactionResult {
        
        // Verify ownership before transfer
        let owner = try await getNFTOwner(collection, tokenId: tokenId)
        guard owner == from.getScriptHash() else {
            throw NFTError.notOwner
        }
        
        let nft = NonFungibleToken(scriptHash: collection, epicchainSwift: epicchainSwift)
        
        let transaction = try await nft
            .transfer(from, to, 1, [tokenId]) // amount is 1 for NFTs
            .signers(AccountSigner.calledByEntry(from))
            .systemFee(options.systemFee)
            .networkFee(options.networkFee)
            .sign()
        
        return try await transaction.send()
    }
    
    // Batch NFT operations
    func batchNFTTransfer(
        from: Account,
        transfers: [NFTTransfer],
        options: BatchNFTTransferOptions = .default
    ) async throws -> [TransactionResult] {
        
        // Group transfers by collection for efficiency
        let transfersByCollection = Dictionary(grouping: transfers) { $0.collection }
        
        var results: [TransactionResult] = []
        
        for (collection, collectionTransfers) in transfersByCollection {
            let tokenIds = collectionTransfers.map { $0.tokenId }
            
            let nft = NonFungibleToken(scriptHash: collection, epicchainSwift: epicchainSwift)
            
            // Single transaction for all transfers in this collection
            let transaction = try await nft
                .transfer(from, transfers.first!.recipient, 1, tokenIds)
                .signers(AccountSigner.calledByEntry(from))
                .systemFee(options.systemFee)
                .networkFee(options.networkFee)
                .sign()
            
            let result = try await transaction.send()
            results.append(result)
        }
        
        return results
    }
}

// XEP-11 data structures
public struct NFTCollectionInfo {
    let hash: Hash160
    let symbol: String
    let decimals: Int
    let totalSupply: Int
    let name: String?
    let description: String?
    let externalURL: URL?
}

public struct NFTTokenMetadata {
    let tokenId: Int
    let collection: Hash160
    let properties: [String: Any]
    let name: String?
    let description: String?
    let image: String?
    let attributes: [NFTAttribute]
}

public struct NFTAttribute {
    let traitType: String
    let value: Any
    let displayType: DisplayType?
}

public enum DisplayType {
    case string
    case number
    case date
    case boostPercentage
    case boostNumber
}

---

🔐 Security

Secure Key Management

// Enterprise-grade key management
public class SecureKeyManager {
    private let security: SecurityManager
    private let keychain: KeychainManager
    private let secureEnclave: SecureEnclaveManager?
    
    init(securityLevel: SecurityLevel = .high) {
        self.security = SecurityManager.shared
        self.keychain = KeychainManager(service: "com.yourapp.epicchain")
        
        if SecureEnclaveManager.isAvailable {
            self.secureEnclave = SecureEnclaveManager()
        } else {
            self.secureEnclave = nil
        }
        
        configureSecurity(securityLevel)
    }
    
    // Generate secure key pair based on security level
    func generateKeyPair(securityLevel: SecurityLevel) throws -> SecureECKeyPair {
        switch securityLevel {
        case .standard:
            return try SecureECKeyPair.createEcKeyPair()
            
        case .high:
            guard let secureEnclave = secureEnclave else {
                throw SecurityError.secureEnclaveUnavailable
            }
            return try secureEnclave.generateKeyPair()
            
        case .maximum:
            // Use hardware security module or specialized hardware
            return try generateHSMKeyPair()
        }
    }
    
    // Store encrypted private key
    func storePrivateKey(
        _ privateKey: Data,
        for account: Hash160,
        encryptionKey: Data,
        biometricProtection: Bool = false
    ) throws {
        
        // Encrypt the private key
        let encryptedKey = try security.encryptPrivateKey(privateKey, with: encryptionKey)
        
        // Store in appropriate location based on security level
        if biometricProtection {
            try keychain.storeWithBiometry(
                encryptedKey,
                for: account.string,
                context: "EpicChain Transaction Signing"
            )
        } else {
            try keychain.store(encryptedKey, for: account.string)
        }
        
        // Clear sensitive data from memory
        security.zeroData(&privateKey)
        security.zeroData(&encryptedKey)
    }
    
    // Retrieve and decrypt private key
    func retrievePrivateKey(
        for account: Hash160,
        decryptionKey: Data,
        biometricContext: LAContext? = nil
    ) throws -> Data {
        
        // Retrieve encrypted key
        let encryptedKey: Data
        if let context = biometricContext {
            encryptedKey = try keychain.retrieveWithBiometry(
                for: account.string,
                context: context
            )
        } else {
            encryptedKey = try keychain.retrieve(for: account.string)
        }
        
        // Decrypt the key
        let privateKey = try security.decryptPrivateKey(encryptedKey, with: decryptionKey)
        
        return privateKey
    }
}

// Biometric authentication integration
public class BiometricAuthManager {
    private let context = LAContext()
    private let keychain: KeychainManager
    
    init() {
        self.keychain = KeychainManager(service: "com.yourapp.epicchain")
    }
    
    // Check biometric availability
    var isBiometricAvailable: Bool {
        var error: NSError?
        return context.canEvaluatePolicy(.deviceOwnerAuthenticationWithBiometrics, error: &error)
    }
    
    // Authenticate with biometrics
    func authenticateWithBiometrics(reason: String = "Access your EpicChain wallet") async throws -> Bool {
        return try await withCheckedThrowingContinuation { continuation in
            context.evaluatePolicy(.deviceOwnerAuthenticationWithBiometrics, localizedReason: reason) { success, error in
                if let error = error {
                    continuation.resume(throwing: error)
                } else {
                    continuation.resume(returning: success)
                }
            }
        }
    }
    
    // Store sensitive data with biometric protection
    func storeWithBiometricProtection(_ data: Data, for key: String) throws {
        try keychain.storeWithBiometry(
            data,
            for: key,
            context: context,
            accessControl: .userPresence
        )
    }
}

Transaction Security

// Transaction security and verification
public class TransactionSecurityManager {
    private let epicchainSwift: EpicChainSwift
    private let security: SecurityManager
    private let threatDetection: ThreatDetectionEngine
    
    init(epicchainSwift: EpicChainSwift) {
        self.epicchainSwift = epicchainSwift
        self.security = SecurityManager.shared
        self.threatDetection = ThreatDetectionEngine()
    }
    
    // Comprehensive transaction verification
    func verifyTransaction(
        _ transaction: Transaction,
        for account: Account,
        context: VerificationContext
    ) async throws -> VerificationResult {
        
        var warnings: [SecurityWarning] = []
        var errors: [SecurityError] = []
        
        // 1. Basic structure verification
        try verifyTransactionStructure(transaction)
        
        // 2. Script analysis
        try await verifyScript(transaction.script, context: context)
        
        // 3. Signer verification
        try verifySigners(transaction.signers, account: account)
        
        // 4. Fee verification
        try verifyFees(transaction.systemFee, transaction.networkFee, context: context)
        
        // 5. Threat detection
        let threats = try await threatDetection.analyzeTransaction(transaction)
        warnings.append(contentsOf: threats.warnings)
        errors.append(contentsOf: threats.errors)
        
        // 6. Contract interaction analysis
        if let contractHash = extractContractHash(transaction.script) {
            try await verifyContractInteraction(contractHash, context: context)
        }
        
        return VerificationResult(
            isValid: errors.isEmpty,
            warnings: warnings,
            errors: errors,
            riskLevel: calculateRiskLevel(warnings: warnings, errors: errors)
        )
    }
    
    // Real-time threat monitoring
    func monitorForThreats(account: Account) -> AnyPublisher<ThreatAlert, Never> {
        return threatDetection.monitorAccount(account.getScriptHash())
    }
}

// Security verification structures
public struct VerificationContext {
    let purpose: TransactionPurpose
    let allowedContracts: [Hash160]
    let maxValue: Int
    let requireConfirmation: Bool
    let securityLevel: SecurityLevel
    
    static let standard = VerificationContext(
        purpose: .general,
        allowedContracts: [],
        maxValue: Int.max,
        requireConfirmation: false,
        securityLevel: .standard
    )
    
    static let highValue = VerificationContext(
        purpose: .assetTransfer,
        allowedContracts: [],
        maxValue: 1000000000, // 10 EpicChain
        requireConfirmation: true,
        securityLevel: .high
    )
}

public struct VerificationResult {
    let isValid: Bool
    let warnings: [SecurityWarning]
    let errors: [SecurityError]
    let riskLevel: RiskLevel
    let recommendation: String?
}

public enum RiskLevel {
    case low
    case medium
    case high
    case critical
}

---

⚡ Performance

Optimization Techniques

// Performance optimization manager
public class PerformanceManager {
    private let cache: MultiLevelCache
    private let optimizer: TransactionOptimizer
    private let monitor: PerformanceMonitor
    
    init() {
        self.cache = MultiLevelCache()
        self.optimizer = TransactionOptimizer()
        self.monitor = PerformanceMonitor()
        
        setupOptimizations()
    }
    
    private func setupOptimizations() {
        // Configure hash caching
        HashCache.shared.maxCacheSize = 10000
        HashCache.shared.compressionEnabled = true
        
        // Configure serialization optimizations
        BinarySerialization.enableOptimizations()
        
        // Setup background compression
        setupBackgroundCompression()
    }
    
    // Batch transaction optimization
    func optimizeTransactionBatch(_ transactions: [Transaction]) -> [Transaction] {
        return optimizer.optimizeBatch(transactions)
    }
    
    // Cache management
    func preloadFrequentData(accounts: [Hash160]) async {
        await withTaskGroup(of: Void.self) { group in
            for account in accounts {
                group.addTask {
                    // Preload account balances
                    _ = try? await self.cache.getAccountBalances(account)
                    
                    // Preload frequent contracts
                    _ = try? await self.cache.getContractManifest(EpicChainToken.SCRIPT_HASH)
                }
            }
        }
    }
}

// Multi-level caching system
public class MultiLevelCache {
    private let memoryCache: NSCache<NSString, AnyObject>
    private let diskCache: DiskCache
    private let networkCache: NetworkCache
    
    init() {
        self.memoryCache = NSCache()
        self.diskCache = DiskCache()
        self.networkCache = NetworkCache()
        
        configureMemoryCache()
    }
    
    private func configureMemoryCache() {
        memoryCache.countLimit = 1000
        memoryCache.totalCostLimit = 50 * 1024 * 1024 // 50MB
    }
    
    // Get data with multi-level cache fallthrough
    func get<T: Codable>(_ key: String, type: T.Type) async throws -> T {
        // Check memory cache first
        if let cached = memoryCache.object(forKey: key as NSString) as? T {
            monitor.hit(.memory)
            return cached
        }
        
        // Check disk cache
        if let diskCached = try? diskCache.get(key, type: type) {
            // Store in memory cache for future access
            memoryCache.setObject(diskCached as AnyObject, forKey: key as NSString)
            monitor.hit(.disk)
            return diskCached
        }
        
        // Fetch from network
        let networkData = try await networkCache.get(key, type: type)
        
        // Store in both caches
        memoryCache.setObject(networkData as AnyObject, forKey: key as NSString)
        try diskCache.set(networkData, for: key)
        
        monitor.hit(.network)
        return networkData
    }
}

Memory Management

// Secure memory management
public class SecureMemoryManager {
    private var protectedRegions: [ProtectedMemoryRegion] = []
    private let zeroingQueue = DispatchQueue(label: "com.epicchain.secure-memory-zeroing")
    
    // Allocate protected memory region
    func allocateProtectedRegion(size: Int, autoZeroing: Bool = true) -> ProtectedMemoryRegion {
        let region = ProtectedMemoryRegion(size: size)
        
        if autoZeroing {
            setupAutoZeroing(for: region)
        }
        
        protectedRegions.append(region)
        return region
    }
    
    // Zero sensitive data on background thread
    private func setupAutoZeroing(for region: ProtectedMemoryRegion) {
        zeroingQueue.asyncAfter(deadline: .now() + 30.0) { [weak self] in
            region.zero()
            self?.protectedRegions.removeAll { $0.id == region.id }
        }
    }
    
    // Emergency zero all protected regions
    func emergencyZeroAll() {
        zeroingQueue.sync {
            for region in protectedRegions {
                region.zero()
            }
            protectedRegions.removeAll()
        }
    }
}

// Protected memory region implementation
public class ProtectedMemoryRegion {
    let id = UUID()
    private let size: Int
    private let pointer: UnsafeMutableRawPointer
    private let protection: MemoryProtection
    
    init(size: Int, protection: MemoryProtection = .readWrite) {
        self.size = size
        self.protection = protection
        self.pointer = UnsafeMutableRawPointer.allocate(byteCount: size, alignment: 1)
        
        // Set memory protection
        setMemoryProtection()
    }
    
    // Zero the memory region
    func zero() {
        pointer.initializeMemory(as: UInt8.self, repeating: 0, count: size)
    }
    
    deinit {
        zero()
        pointer.deallocate()
    }
}

---

🧪 Testing

Comprehensive Test Suite

import XCTest
import EpicChainSwift
import Combine

// Main test suite
class EpicChainSwiftTests: XCTestCase {
    var epicchainSwift: EpicChainSwift!
    var testAccount: Account!
    var cancellables: Set<AnyCancellable> = []
    
    override func setUp() async throws {
        // Use testnet for testing
        let testNetURL = URL(string: "https://testnet1-seed.epic-chain.org:10111")!
        epicchainSwift = EpicChainSwift.build(HttpService(url: testNetURL))
        
        // Create test account with test funds
        testAccount = try Account.createNewAccount()
        
        // Fund the test account (in real scenario, use testnet faucet)
        try await fundTestAccount()
    }
    
    override func tearDown() {
        cancellables.removeAll()
    }
    
    // Test account creation and management
    func testAccountCreation() throws {
        // Test secure account creation
        let secureAccount = try Account.createNewAccount()
            .securedWith(securityLevel: .high)
        
        XCTAssertFalse(secureAccount.getAddress().isEmpty)
        XCTAssertTrue(secureAccount.verify())
    }
    
    // Test transaction building and signing
    func testTransactionBuilding() async throws {
        let script = try ScriptBuilder()
            .contractCall(EpicChainToken.SCRIPT_HASH, method: "symbol", params: [])
            .toArray()
        
        let transaction = try await TransactionBuilder(epicchainSwift)
            .script(script)
            .signers(AccountSigner.calledByEntry(testAccount))
            .sign()
        
        XCTAssertFalse(transaction.hash.string.isEmpty)
        XCTAssertTrue(transaction.verify())
    }
    
    // Test contract interactions
    func testContractInteraction() async throws {
        let contractHash = try Hash160("0x1a70eac53f5882e40dd90f55463cce31a9f72cd4")
        let contract = SmartContract(scriptHash: contractHash, epicchainSwift: epicchainSwift)
        
        let result = try await contract.callInvokeFunction(
            "resolve",
            [ContractParameter.string("test.epicchain")],
            []
        )
        
        XCTAssertEqual(result.state, .halt)
    }
    
    // Test performance with large datasets
    func testPerformanceLargeBatch() {
        measure {
            let expectation = self.expectation(description: "Batch completion")
            
            Task {
                // Perform batch operations
                let transactions = try await createBatchTransactions(count: 100)
                let results = try await sendBatchTransactions(transactions)
                
                XCTAssertEqual(results.count, 100)
                expectation.fulfill()
            }
            
            waitForExpectations(timeout: 30.0)
        }
    }
}

// Security-specific tests
class SecurityTests: XCTestCase {
    func testSecureMemoryManagement() {
        let secureManager = SecureMemoryManager()
        let region = secureManager.allocateProtectedRegion(size: 256)
        
        // Write sensitive data
        region.withUnsafeBytes { pointer in
            // Simulate writing private key
            pointer.initializeMemory(as: UInt8.self, repeating: 0xAA, count: 256)
        }
        
        // Zero the region
        region.zero()
        
        // Verify data is zeroed
        region.withUnsafeBytes { pointer in
            for byte in pointer {
                XCTAssertEqual(byte, 0)
            }
        }
    }
    
    func testTimingAttackResistance() {
        let attackerControlled = "attacker_input"
        let secretValue = "secret_value"
        
        // Measure time for comparison
        let startTime = Date()
        
        for _ in 0..<1000 {
            _ = SecurityUtilities.constantTimeCompare(attackerControlled, secretValue)
        }
        
        let duration = Date().timeIntervalSince(startTime)
        
        // Timing should be consistent regardless of input
        XCTAssertLessThan(duration, 1.0) // Should complete quickly
    }
}

// Integration tests
class IntegrationTests: XCTestCase {
    var integrationManager: IntegrationTestManager!
    
    override func setUp() {
        integrationManager = IntegrationTestManager()
    }
    
    func testEndToEndTransactionFlow() async throws {
        // Test complete transaction flow
        let result = try await integrationManager.testCompleteFlow()
        
        XCTAssertTrue(result.success)
        XCTAssertNotNil(result.transactionHash)
        XCTAssertNotNil(result.blockConfirmation)
    }
    
    func testErrorConditions() async throws {
        // Test various error conditions
        let invalidHash = try Hash256("0xinvalid")
        
        do {
            _ = try await integrationManager.getTransaction(invalidHash)
            XCTFail("Should have thrown error")
        } catch {
            XCTAssertTrue(error is EpicChainError)
        }
    }
}

Test Utilities

// Test utilities and helpers
public class TestUtilities {
    
    // Create mock blockchain state for testing
    static func createMockBlockchainState(height: Int = 1000) -> BlockchainState {
        return BlockchainState(
            height: height,
            timestamp: Date(),
            validators: createMockValidators(),
            network: .testNet
        )
    }
    
    // Create test transactions
    static func createTestTransaction(
        script: Bytes = [],
        signers: [Signer] = [],
        systemFee: Int = 1000000,
        networkFee: Int = 0
    ) -> Transaction {
        
        return Transaction(
            version: 0,
            nonce: UInt32.random(in: 0...UInt32.max),
            systemFee: systemFee,
            networkFee: networkFee,
            validUntilBlock: 1000,
            signers: signers,
            script: script,
            witnesses: []
        )
    }
    
    // Mock network service for testing
    static func createMockNetworkService() -> HttpService {
        let configuration = URLSessionConfiguration.ephemeral
        configuration.protocolClasses = [MockURLProtocol.self]
        
        return HttpService(
            url: URL(string: "https://mock.epic-chain.org")!,
            configuration: configuration
        )
    }
}

// Mock URL protocol for testing
class MockURLProtocol: URLProtocol {
    static var mockResponses: [URL: Result<Data, Error>] = [:]
    
    override class func canInit(with request: URLRequest) -> Bool {
        return true
    }
    
    override class func canonicalRequest(for request: URLRequest) -> URLRequest {
        return request
    }
    
    override func startLoading() {
        if let url = request.url, let result = Self.mockResponses[url] {
            switch result {
            case .success(let data):
                client?.urlProtocol(self, didLoad: data)
                client?.urlProtocolDidFinishLoading(self)
            case .failure(let error):
                client?.urlProtocol(self, didFailWithError: error)
            }
        } else {
            client?.urlProtocol(self, didFailWithError: URLError(.badServerResponse))
        }
    }
    
    override func stopLoading() {
        // Required override
    }
}

---

🚀 Deployment

Production Checklist

// Production deployment manager
public class ProductionDeploymentManager {
    private let security: SecurityManager
    private let config: ProductionConfig
    
    init(config: ProductionConfig) {
        self.security = SecurityManager.shared
        self.config = config
    }
    
    // Prepare for production deployment
    func prepareForProduction() throws {
        // 1. Validate security configuration
        try validateSecurityConfiguration()
        
        // 2. Enable production security features
        try enableProductionSecurity()
        
        // 3. Configure performance optimizations
        configureProductionPerformance()
        
        // 4. Set up monitoring and logging
        setupProductionMonitoring()
        
        // 5. Verify network configuration
        try verifyNetworkConfiguration()
    }
    
    // Validate production readiness
    func validateProductionReadiness() -> ProductionReadinessReport {
        var report = ProductionReadinessReport()
        
        // Check security features
        if !security.isProductionReady {
            report.addIssue(.critical("Security not production ready"))
        }
        
        // Check performance
        if !PerformanceManager.shared.isOptimizedForProduction {
            report.addIssue(.warning("Performance not fully optimized"))
        }
        
        // Check network connectivity
        if !NetworkManager.shared.hasRedundantConnections {
            report.addIssue(.warning("No redundant node connections"))
        }
        
        return report
    }
}

// Production configuration
public struct ProductionConfig {
    let securityLevel: SecurityLevel
    let performanceLevel: PerformanceLevel
    let monitoringEnabled: Bool
    let backupEnabled: Bool
    let disasterRecovery: DisasterRecoveryPlan
    
    static let standard = ProductionConfig(
        securityLevel: .high,
        performanceLevel: .optimized,
        monitoringEnabled: true,
        backupEnabled: true,
        disasterRecovery: .standard
    )
}

// Production readiness report
public struct ProductionReadinessReport {
    var issues: [ProductionIssue] = []
    var warnings: [ProductionWarning] = []
    var recommendations: [String] = []
    
    var isReady: Bool {
        return issues.isEmpty
    }
    
    mutating func addIssue(_ issue: ProductionIssue) {
        issues.append(issue)
    }
}

Monitoring and Analytics

// Production monitoring system
public class ProductionMonitor {
    private let metrics: MetricsCollector
    private let alertManager: AlertManager
    private let logger: Logger
    
    init() {
        self.metrics = MetricsCollector()
        self.alertManager = AlertManager()
        self.logger = Logger()
        
        setupMonitoring()
    }
    
    private func setupMonitoring() {
        // Set up performance monitoring
        metrics.startCollecting()
        
        // Set up error tracking
        setupErrorTracking()
        
        // Set up security monitoring
        setupSecurityMonitoring()
    }
    
    // Track application metrics
    func trackTransactionMetrics(_ transaction: Transaction, duration: TimeInterval) {
        metrics.recordTransaction(
            hash: transaction.hash,
            duration: duration,
            fees: transaction.systemFee + transaction.networkFee,
            success: true
        )
    }
    
    // Monitor for anomalies
    func monitorForAnomalies() -> AnyPublisher<Anomaly, Never> {
        return AnomalyDetector()
            .anomalies
            .handleEvents(receiveOutput: { [weak self] anomaly in
                self?.handleAnomaly(anomaly)
            })
            .eraseToAnyPublisher()
    }
}

// Metrics collection
public class MetricsCollector {
    private var transactions: [TransactionMetric] = []
    private var performance: [PerformanceMetric] = []
    private var errors: [ErrorMetric] = []
    
    func recordTransaction(hash: Hash256, duration: TimeInterval, fees: Int, success: Bool) {
        let metric = TransactionMetric(
            hash: hash,
            timestamp: Date(),
            duration: duration,
            fees: fees,
            success: success
        )
        transactions.append(metric)
        
        // Keep only last 1000 transactions
        if transactions.count > 1000 {
            transactions.removeFirst()
        }
    }
    
    func generateReport() -> MetricsReport {
        return MetricsReport(
            transactionCount: transactions.count,
            successRate: calculateSuccessRate(),
            averageDuration: calculateAverageDuration(),
            totalFees: calculateTotalFees(),
            performanceMetrics: performance
        )
    }
}

---

🤝 Contributing

Development Setup

// Development environment setup
public class DevelopmentSetup {
    
    // Setup development environment
    func setupDevelopmentEnvironment() throws {
        // 1. Clone the repository
        try cloneRepository()
        
        // 2. Install dependencies
        try installDependencies()
        
        // 3. Configure development settings
        try configureDevelopmentSettings()
        
        // 4. Run initial tests
        try runInitialTests()
    }
    
    // Create development branch
    func createFeatureBranch(featureName: String) throws {
        try runCommand("git checkout -b feature/\(featureName.sanitized())")
    }
    
    // Run development tests
    func runDevelopmentTests() throws -> TestResults {
        return try TestRunner().runTests(suite: .development)
    }
}

// Contribution guidelines
public struct ContributionGuidelines {
    let codingStandards: CodingStandards
    let testingRequirements: TestingRequirements
    let documentationRequirements: DocumentationRequirements
    let securityRequirements: SecurityRequirements
    
    static let current = ContributionGuidelines(
        codingStandards: .swiftFormat,
        testingRequirements: .highCoverage,
        documentationRequirements: .comprehensive,
        securityRequirements: .strict
    )
}

// Code review checklist
public struct CodeReviewChecklist {
    let security: [SecurityCheck]
    let performance: [PerformanceCheck]
    let quality: [QualityCheck]
    
    func validate(_ code: SourceCode) -> CodeReviewResult {
        var result = CodeReviewResult()
        
        for check in security {
            if !check.validate(code) {
                result.addSecurityIssue(check.issue)
            }
        }
        
        return result
    }
}

Security Contribution Guidelines

// Security-focused contribution process
public class SecurityContributionProcess {
    
    // Submit security-focused contribution
    func submitSecurityContribution(_ contribution: SecurityContribution) async throws {
        // 1. Pre-submission security review
        try await performSecurityReview(contribution)
        
        // 2. Run security tests
        try runSecurityTests(contribution)
        
        // 3. Submit for security audit
        try await submitForSecurityAudit(contribution)
        
        // 4. Merge after approval
        try await mergeAfterApproval(contribution)
    }
    
    // Security review process
    private func performSecurityReview(_ contribution: SecurityContribution) async throws {
        let reviewer = SecurityReviewer()
        let review = try await reviewer.review(contribution)
        
        guard review.approved else {
            throw SecurityReviewError.reviewFailed(issues: review.issues)
        }
    }
}

// Security vulnerability reporting
public class VulnerabilityReporting {
    private let encryption: EncryptionManager
    private let secureChannel: SecureChannel
    
    init() {
        self.encryption = EncryptionManager()
        self.secureChannel = SecureChannel()
    }
    
    // Report security vulnerability
    func reportVulnerability(_ report: VulnerabilityReport) async throws -> ReportAcknowledgement {
        // Encrypt the report
        let encryptedReport = try encryption.encrypt(report)
        
        // Submit through secure channel
        let acknowledgement = try await secureChannel.submitReport(encryptedReport)
        
        return acknowledgement
    }
    
    // Check vulnerability status
    func checkVulnerabilityStatus(_ reportId: String) async throws -> VulnerabilityStatus {
        return try await secureChannel.getStatus(reportId)
    }
}

---

📄 License

License Management

// License compliance manager
public class LicenseComplianceManager {
    private let licenses: [LibraryLicense]
    private let compliance: ComplianceChecker
    
    init() {
        self.licenses = loadLicenses()
        self.compliance = ComplianceChecker()
    }
    
    // Verify license compliance
    func verifyCompliance() throws -> ComplianceReport {
        let report = ComplianceReport()
        
        for license in licenses {
            if !compliance.isCompliant(license) {
                report.addViolation(license)
            }
        }
        
        return report
    }
    
    // Generate license notices
    func generateLicenseNotices() -> String {
        return licenses.map { license in
            """
            \(license.libraryName) - \(license.licenseType)
            \(license.licenseText)
            
            """
        }.joined()
    }
}

// Open source license information
public struct LibraryLicense {
    let libraryName: String
    let version: String
    let licenseType: LicenseType
    let licenseText: String
    let copyright: String
}

public enum LicenseType {
    case mit
    case apache2
    case bsd3
    case gpl
    case custom(String)
}

---

🙏 Acknowledgements

Contributors

// Project acknowledgement system
public class AcknowledgementSystem {
    private let contributors: [Contributor]
    private let sponsors: [Sponsor]
    private let dependencies: [Dependency]
    
    init() {
        self.contributors = loadContributors()
        self.sponsors = loadSponsors()
        self.dependencies = loadDependencies()
    }
    
    // Generate acknowledgements
    func generateAcknowledgements() -> Acknowledgements {
        return Acknowledgements(
            contributors: contributors,
            sponsors: sponsors,
            dependencies: dependencies,
            specialThanks: specialThanks
        )
    }
}

// Contributor recognition
public struct Contributor {
    let name: String
    let contributions: [ContributionType]
    let since: Date
    let impact: ContributorImpact
}

public enum ContributionType {
    case code
    case documentation
    case testing
    case security
    case maintenance
    case community
}

public enum ContributorImpact {
    case low
    case medium
    case high
    case critical
}

Special Thanks

The EpicChainSwift project acknowledges the following individuals and organizations for their invaluable contributions:

• The EpicChain Core Team for their continuous support and technical guidance
• Security Researchers who helped identify and fix vulnerabilities
• Early Adopters who provided real-world testing and feedback
• Open Source Community for the incredible tools and libraries that made this project possible

Sponsors and Backers

This project is supported by:

• GrantShares - Primary development funding
• EpicChain Foundation - Ecosystem development grants
• Community Donors - Individual contributions and support

---

📞 Support

Getting Help

• Documentation: docs.epicchain.org/swift
• Community Forum: community.epicchain.org
• GitHub Issues: github.com/epicchainlabs/epicchain-swift/issues
• Security Reports: security@epicchain.org

Professional Support

For enterprise support and professional services:

• Technical Support: support@epicchain.org
• Partnership Inquiries: partnerships@epicchain.org
• Security Consulting: security-consulting@epicchain.org

---

EpicChain Swift - Building the future of blockchain on Apple platforms 🚀

Documentation • Examples • API Reference • Security