Initial Commit

Author: Christian Elies

.gitignore

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+.DS_Store
+/.build
+/Packages
+/*.xcodeproj
+xcuserdata/

.swiftpm/xcode/package.xcworkspace/contents.xcworkspacedata

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+// swift-tools-version:5.1
+// The swift-tools-version declares the minimum version of Swift required to build this package.
+
+import PackageDescription
+
+let package = Package(
+    name: "RemoteImage",
+    platforms: [
+        .iOS(.v13)
+    ],
+    products: [
+        .library(
+            name: "RemoteImage",
+            targets: ["RemoteImage"]),
+    ],
+    targets: [
+        .target(
+            name: "RemoteImage",
+            dependencies: []),
+        .testTarget(
+            name: "RemoteImageTests",
+            dependencies: ["RemoteImage"]),
+    ]
+)

Package.swift

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+# RemoteImage
+
+[![Swift5](https://img.shields.io/badge/swift5-compatible-green.svg?longCache=true&style=flat-square)](https://developer.apple.com/swift)
+[![Platform](https://img.shields.io/badge/platform-iOS-lightgrey.svg?longCache=true&style=flat-square)](https://www.apple.com/de/ios)
+[![License](https://img.shields.io/badge/license-MIT-lightgrey.svg?longCache=true&style=flat-square)](https://en.wikipedia.org/wiki/MIT_License)
+
+This Swift package provides a wrapper view around the existing **SwiftUI** `Image view` which adds support for showing and caching remote images.
+In addition you can specify a loading and error view.
+
+## Installation
+
+Add this Swift package in Xcode using its Github repository url. (File > Swift Packages > Add Package Dependency...)
+
+## How to use
+
+Just pass your remote image url and `ViewBuilder`s for the error, image and loading state to the initializer. That's it 🎉
+
+Clear the image cache through `RemoteImageService.cache.removeAllObjects()`.
+
+## Example
+
+The following code truly highlights the **simplicity** of this view:
+
+```swift
+let url = URL(string: "https://images.unsplash.com/photo-1524419986249-348e8fa6ad4a?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=1950&q=80")!
+
+RemoteImage(url: url, errorView: { error in
+    Text(error.localizedDescription)
+}, imageView: { image in
+    image
+    .resizable()
+    .aspectRatio(contentMode: .fit)
+}, loadingView: {
+    Text("Loading ...")
+})
+```

README.md

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+//
+//  RemoteImageServiceError.swift
+//  RemoteImage
+//
+//  Created by Christian Elies on 11.08.19.
+//  Copyright © 2019 Christian Elies. All rights reserved.
+//
+
+import Foundation
+
+enum RemoteImageServiceError: Error {
+    case couldNotCreateImage
+}
+
+extension RemoteImageServiceError: LocalizedError {
+    var errorDescription: String? {
+        return "Could not create image from received data"
+    }
+}

Sources/RemoteImage/private/Models/RemoteImageServiceError.swift

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+//
+//  RemoteImageState.swift
+//  RemoteImage
+//
+//  Created by Christian Elies on 11.08.19.
+//  Copyright © 2019 Christian Elies. All rights reserved.
+//
+
+import UIKit
+
+enum RemoteImageState {
+    case error(_ error: Error)
+    case image(_ image: UIImage)
+    case loading
+}
+
+extension RemoteImageState: Equatable {
+    static func == (lhs: RemoteImageState, rhs: RemoteImageState) -> Bool {
+        switch (lhs, rhs) {
+            case (.error(let lhsError), .error(let rhsError)):
+                return (lhsError as NSError) == (rhsError as NSError)
+            case (.image(let lhsImage), .image(let rhsImage)):
+                return lhsImage == rhsImage
+            case (.loading, .loading):
+                return true
+            default:
+                return false
+        }
+    }
+}

Sources/RemoteImage/private/Models/RemoteImageState.swift

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+//
+//  RemoteImageService.swift
+//  RemoteImage
+//
+//  Created by Christian Elies on 11.08.19.
+//  Copyright © 2019 Christian Elies. All rights reserved.
+//
+
+import Combine
+import UIKit
+
+public final class RemoteImageService: ObservableObject {
+    private var cancellable: AnyCancellable?
+    
+    var state: RemoteImageState = .loading {
+        didSet {
+            objectWillChange.send()
+        }
+    }
+    
+    public static let cache = NSCache<NSURL, UIImage>()
+    
+    public let objectWillChange = PassthroughSubject<Void, Never>()
+    
+    func fetchImage(atURL url: URL) {
+        cancellable?.cancel()
+        
+        if let image = RemoteImageService.cache.object(forKey: url as NSURL) {
+            state = .image(image)
+            return
+        }
+        
+        let urlSession = URLSession.shared
+        let urlRequest = URLRequest(url: url)
+        
+        cancellable = urlSession.dataTaskPublisher(for: urlRequest)
+            .map { UIImage(data: $0.data) }
+            .receive(on: RunLoop.main)
+            .sink(receiveCompletion: { completion in
+                switch completion {
+                    case .failure(let failure):
+                        self.state = .error(failure)
+                    default: ()
+                }
+            }) { image in
+                if let image = image {
+                    RemoteImageService.cache.setObject(image, forKey: url as NSURL)
+                    self.state = .image(image)
+                } else {
+                    self.state = .error(RemoteImageServiceError.couldNotCreateImage)
+                }
+            }
+    }
+}

Sources/RemoteImage/public/Services/RemoteImageService.swift

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+//
+//  RemoteImage.swift
+//  RemoteImage
+//
+//  Created by Christian Elies on 11.08.19.
+//  Copyright © 2019 Christian Elies. All rights reserved.
+//
+
+import Combine
+import SwiftUI
+
+public struct RemoteImage<ErrorView: View, ImageView: View, LoadingView: View>: View {
+    private let url: URL
+    private let errorView: (Error) -> ErrorView
+    private let imageView: (Image) -> ImageView
+    private let loadingView: () -> LoadingView
+    @ObservedObject private var service: RemoteImageService = RemoteImageService()
+    
+    public var body: AnyView {
+        switch service.state {
+            case .error(let error):
+                return AnyView(
+                    errorView(error)
+                )
+            case .image(let image):
+                return AnyView(
+                    self.imageView(Image(uiImage: image))
+                )
+            case .loading:
+                return AnyView(
+                    loadingView()
+                    .onAppear {
+                        self.service.fetchImage(atURL: self.url)
+                    }
+                )
+        }
+    }
+    
+    public init(url: URL, @ViewBuilder errorView: @escaping (Error) -> ErrorView, @ViewBuilder imageView: @escaping (Image) -> ImageView, @ViewBuilder loadingView: @escaping () -> LoadingView) {
+        self.url = url
+        self.errorView = errorView
+        self.imageView = imageView
+        self.loadingView = loadingView
+    }
+}
+
+#if DEBUG
+struct RemoteImage_Previews: PreviewProvider {
+    static var previews: some View {
+        let url = URL(string: "https://images.unsplash.com/photo-1524419986249-348e8fa6ad4a?ixlib=rb-1.2.1&ixid=eyJhcHBfaWQiOjEyMDd9&auto=format&fit=crop&w=1950&q=80")!
+        return RemoteImage(url: url, errorView: { error in
+            Text(error.localizedDescription)
+        }, imageView: { image in
+            image
+        }, loadingView: {
+            Text("Loading ...")
+        })
+    }
+}
+#endif

Sources/RemoteImage/public/Views/RemoteImage.swift

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+import XCTest
+
+import RemoteImageTests
+
+var tests = [XCTestCaseEntry]()
+tests += RemoteImageTests.allTests()
+XCTMain(tests)

Tests/LinuxMain.swift

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+import XCTest
+@testable import RemoteImage
+
+final class RemoteImageTests: XCTestCase {
+    func testExample() {
+        // This is an example of a functional test case.
+        // Use XCTAssert and related functions to verify your tests produce the correct
+        // results.
+        XCTAssertEqual("Hello, World!", "Hello, World!")
+    }
+
+    static var allTests = [
+        ("testExample", testExample),
+    ]
+}