Use type-safe keypath constructor in PFRelationState.

Author: nlutsenko

Parse/Internal/Relation/State/PFMutableRelationState.m

@@ -28,7 +28,7 @@ @implementation PFMutableRelationState
 + (NSDictionary *)propertyAttributes {
     NSMutableDictionary *parentAttributes = [[super propertyAttributes] mutableCopy];
 
-    parentAttributes[@"knownObjects"] = [PFPropertyAttributes attributesWithAssociationType:PFPropertyInfoAssociationTypeMutableCopy];
+    parentAttributes[PFRelationStatePropertyName(knownObjects)] = [PFPropertyAttributes attributesWithAssociationType:PFPropertyInfoAssociationTypeMutableCopy];
 
     return parentAttributes;
 }

Parse/Internal/Relation/State/PFRelationState.m

@@ -19,14 +19,12 @@ @implementation PFRelationState
 ///--------------------------------------
 
 + (NSDictionary *)propertyAttributes {
-    return @{
-        @"parent": [PFPropertyAttributes attributesWithAssociationType:PFPropertyInfoAssociationTypeWeak],
-        @"parentClassName": [PFPropertyAttributes attributesWithAssociationType:PFPropertyInfoAssociationTypeCopy],
-        @"parentObjectId": [PFPropertyAttributes attributesWithAssociationType:PFPropertyInfoAssociationTypeCopy],
-        @"targetClass": [PFPropertyAttributes attributesWithAssociationType:PFPropertyInfoAssociationTypeCopy],
-        @"knownObjects": [PFPropertyAttributes attributesWithAssociationType:PFPropertyInfoAssociationTypeCopy],
-        @"key": [PFPropertyAttributes attributesWithAssociationType:PFPropertyInfoAssociationTypeCopy],
-    };
+    return @{ PFRelationStatePropertyName(parent): [PFPropertyAttributes attributesWithAssociationType:PFPropertyInfoAssociationTypeWeak],
+              PFRelationStatePropertyName(parentClassName): [PFPropertyAttributes attributesWithAssociationType:PFPropertyInfoAssociationTypeCopy],
+              PFRelationStatePropertyName(parentObjectId): [PFPropertyAttributes attributesWithAssociationType:PFPropertyInfoAssociationTypeCopy],
+              PFRelationStatePropertyName(targetClass): [PFPropertyAttributes attributesWithAssociationType:PFPropertyInfoAssociationTypeCopy],
+              PFRelationStatePropertyName(knownObjects): [PFPropertyAttributes attributesWithAssociationType:PFPropertyInfoAssociationTypeCopy],
+              PFRelationStatePropertyName(key): [PFPropertyAttributes attributesWithAssociationType:PFPropertyInfoAssociationTypeCopy] };
 }
 
 ///--------------------------------------

Parse/Internal/Relation/State/PFRelationState_Private.h

@@ -9,6 +9,17 @@
 
 #import "PFRelationState.h"
 
+#import "PFMacros.h"
+
+/**
+ Returns NSString representation of a property.
+
+ @param NAME The name of the property.
+
+ @return NSString representation of a given property.
+ */
+#define PFRelationStatePropertyName(NAME) @keypath(PFRelationState, NAME)
+
 @interface PFRelationState() {
 @protected
     __weak PFObject *_parent;