Mantle/MTLJSONAdapter.m - nest-client-apple-tv/5.9.0/Mantle - Git at Google

 //
 //  MTLJSONAdapter.m
 //  Mantle
 //
 //  Created by Justin Spahr-Summers on 2013-02-12.
 //  Copyright (c) 2013 GitHub. All rights reserved.
 //

 #import "MTLJSONAdapter.h"
 #import "MTLModel.h"
 #import "MTLReflection.h"

 NSString * const MTLJSONAdapterErrorDomain = @"MTLJSONAdapterErrorDomain";
 const NSInteger MTLJSONAdapterErrorNoClassFound = 2;
 const NSInteger MTLJSONAdapterErrorInvalidJSONDictionary = 3;
 const NSInteger MTLJSONAdapterErrorInvalidJSONMapping = 4;

 // An exception was thrown and caught.
 const NSInteger MTLJSONAdapterErrorExceptionThrown = 1;

 // Associated with the NSException that was caught.
 static NSString * const MTLJSONAdapterThrownExceptionErrorKey = @"MTLJSONAdapterThrownException";

 @interface MTLJSONAdapter ()

 // The MTLModel subclass being parsed, or the class of `model` if parsing has
 // completed.
 @property (nonatomic, strong, readonly) Class modelClass;

 // A cached copy of the return value of +JSONKeyPathsByPropertyKey.
 @property (nonatomic, copy, readonly) NSDictionary *JSONKeyPathsByPropertyKey;

 // Looks up the NSValueTransformer that should be used for the given key.
 //
 // key - The property key to transform from or to. This argument must not be nil.
 //
 // Returns a transformer to use, or nil to not transform the property.
 - (NSValueTransformer *)JSONTransformerForKey:(NSString *)key;

 @end

 @implementation MTLJSONAdapter

 #pragma mark Convenience methods

 + (id)modelOfClass:(Class)modelClass fromJSONDictionary:(NSDictionary *)JSONDictionary error:(NSError **)error {
 	MTLJSONAdapter *adapter = [[self alloc] initWithJSONDictionary:JSONDictionary modelClass:modelClass error:error];
 	return adapter.model;
 }

 + (NSArray *)modelsOfClass:(Class)modelClass fromJSONArray:(NSArray *)JSONArray error:(NSError **)error {
 	if (JSONArray == nil || ![JSONArray isKindOfClass:NSArray.class]) {
 		if (error != NULL) {
 			NSDictionary *userInfo = @{
 				NSLocalizedDescriptionKey: NSLocalizedString(@"Missing JSON array", @""),
 				NSLocalizedFailureReasonErrorKey: [NSString stringWithFormat:NSLocalizedString(@"%@ could not be created because an invalid JSON array was provided: %@", @""), NSStringFromClass(modelClass), JSONArray.class],
 			};
 			*error = [NSError errorWithDomain:MTLJSONAdapterErrorDomain code:MTLJSONAdapterErrorInvalidJSONDictionary userInfo:userInfo];
 		}
 		return nil;
 	}

 	NSMutableArray *models = [NSMutableArray arrayWithCapacity:JSONArray.count];
 	for (NSDictionary *JSONDictionary in JSONArray){
 		MTLModel *model = [self modelOfClass:modelClass fromJSONDictionary:JSONDictionary error:error];

 		if (model == nil) return nil;

 		[models addObject:model];
 	}

 	return models;
 }

 + (NSDictionary *)JSONDictionaryFromModel:(MTLModel<MTLJSONSerializing> *)model {
 	MTLJSONAdapter *adapter = [[self alloc] initWithModel:model];
 	return adapter.JSONDictionary;
 }

 + (NSArray *)JSONArrayFromModels:(NSArray *)models {
 	NSParameterAssert(models != nil);
 	NSParameterAssert([models isKindOfClass:NSArray.class]);

 	NSMutableArray *JSONArray = [NSMutableArray arrayWithCapacity:models.count];
 	for (MTLModel<MTLJSONSerializing> *model in models) {
 		NSDictionary *JSONDictionary = [self JSONDictionaryFromModel:model];
 		if (JSONDictionary == nil) return nil;

 		[JSONArray addObject:JSONDictionary];
 	}

 	return JSONArray;
 }

 #pragma mark Lifecycle

 - (id)init {
 	NSAssert(NO, @"%@ must be initialized with a JSON dictionary or model object", self.class);
 	return nil;
 }

 - (id)initWithJSONDictionary:(NSDictionary *)JSONDictionary modelClass:(Class)modelClass error:(NSError **)error {
 	NSParameterAssert(modelClass != nil);
 	NSParameterAssert([modelClass isSubclassOfClass:MTLModel.class]);
 	NSParameterAssert([modelClass conformsToProtocol:@protocol(MTLJSONSerializing)]);

 	if (JSONDictionary == nil || ![JSONDictionary isKindOfClass:NSDictionary.class]) {
 		if (error != NULL) {
 			NSDictionary *userInfo = @{
 				NSLocalizedDescriptionKey: NSLocalizedString(@"Missing JSON dictionary", @""),
 				NSLocalizedFailureReasonErrorKey: [NSString stringWithFormat:NSLocalizedString(@"%@ could not be created because an invalid JSON dictionary was provided: %@", @""), NSStringFromClass(modelClass), JSONDictionary.class],
 			};
 			*error = [NSError errorWithDomain:MTLJSONAdapterErrorDomain code:MTLJSONAdapterErrorInvalidJSONDictionary userInfo:userInfo];
 		}
 		return nil;
 	}

 	if ([modelClass respondsToSelector:@selector(classForParsingJSONDictionary:)]) {
 		modelClass = [modelClass classForParsingJSONDictionary:JSONDictionary];
 		if (modelClass == nil) {
 			if (error != NULL) {
 				NSDictionary *userInfo = @{
 					NSLocalizedDescriptionKey: NSLocalizedString(@"Could not parse JSON", @""),
 					NSLocalizedFailureReasonErrorKey: NSLocalizedString(@"No model class could be found to parse the JSON dictionary.", @"")
 				};

 				*error = [NSError errorWithDomain:MTLJSONAdapterErrorDomain code:MTLJSONAdapterErrorNoClassFound userInfo:userInfo];
 			}

 			return nil;
 		}

 		NSAssert([modelClass isSubclassOfClass:MTLModel.class], @"Class %@ returned from +classForParsingJSONDictionary: is not a subclass of MTLModel", modelClass);
 		NSAssert([modelClass conformsToProtocol:@protocol(MTLJSONSerializing)], @"Class %@ returned from +classForParsingJSONDictionary: does not conform to <MTLJSONSerializing>", modelClass);
 	}

 	self = [super init];
 	if (self == nil) return nil;

 	_modelClass = modelClass;
 	_JSONKeyPathsByPropertyKey = [[modelClass JSONKeyPathsByPropertyKey] copy];

 	NSMutableDictionary *dictionaryValue = [[NSMutableDictionary alloc] initWithCapacity:JSONDictionary.count];

 	NSSet *propertyKeys = [self.modelClass propertyKeys];

 	for (NSString *JSONKeyPath in self.JSONKeyPathsByPropertyKey) {
 		if ([propertyKeys containsObject:JSONKeyPath]) continue;

 		if (error != NULL) {
 			NSDictionary *userInfo = @{
 				NSLocalizedDescriptionKey: NSLocalizedString(@"Invalid JSON mapping", nil),
 				NSLocalizedFailureReasonErrorKey: [NSString stringWithFormat:NSLocalizedString(@"%1$@ could not be parsed because its JSON mapping contains illegal property keys.", nil), modelClass]
 			};

 			*error = [NSError errorWithDomain:MTLJSONAdapterErrorDomain code:MTLJSONAdapterErrorInvalidJSONMapping userInfo:userInfo];
 		}

 		return nil;
 	}

 	for (NSString *propertyKey in propertyKeys) {
 		NSString *JSONKeyPath = [self JSONKeyPathForPropertyKey:propertyKey];
 		if (JSONKeyPath == nil) continue;

 		id value;
 		@try {
 			value = [JSONDictionary valueForKeyPath:JSONKeyPath];
 		} @catch (NSException *ex) {
 			if (error != NULL) {
 				NSDictionary *userInfo = @{
 					NSLocalizedDescriptionKey: NSLocalizedString(@"Invalid JSON dictionary", nil),
 					NSLocalizedFailureReasonErrorKey: [NSString stringWithFormat:NSLocalizedString(@"%1$@ could not be parsed because an invalid JSON dictionary was provided for key path \"%2$@\"", nil), modelClass, JSONKeyPath],
 					MTLJSONAdapterThrownExceptionErrorKey: ex
 				};

 				*error = [NSError errorWithDomain:MTLJSONAdapterErrorDomain code:MTLJSONAdapterErrorInvalidJSONDictionary userInfo:userInfo];
 			}

 			return nil;
 		}

 		if (value == nil) continue;

 		@try {
 			NSValueTransformer *transformer = [self JSONTransformerForKey:propertyKey];
 			if (transformer != nil) {
 				// Map NSNull -> nil for the transformer, and then back for the
 				// dictionary we're going to insert into.
 				if ([value isEqual:NSNull.null]) value = nil;
 				value = [transformer transformedValue:value] ?: NSNull.null;
 			}

 			dictionaryValue[propertyKey] = value;
 		} @catch (NSException *ex) {
 			NSLog(@"*** Caught exception %@ parsing JSON key path \"%@\" from: %@", ex, JSONKeyPath, JSONDictionary);

 			// Fail fast in Debug builds.
 			#if DEBUG
 			@throw ex;
 			#else
 			if (error != NULL) {
 				NSDictionary *userInfo = @{
 					NSLocalizedDescriptionKey: ex.description,
 					NSLocalizedFailureReasonErrorKey: ex.reason,
 					MTLJSONAdapterThrownExceptionErrorKey: ex
 				};

 				*error = [NSError errorWithDomain:MTLJSONAdapterErrorDomain code:MTLJSONAdapterErrorExceptionThrown userInfo:userInfo];
 			}

 			return nil;
 			#endif
 		}
 	}

 	_model = [self.modelClass modelWithDictionary:dictionaryValue error:error];
 	if (_model == nil) return nil;

 	return self;
 }

 - (id)initWithModel:(MTLModel<MTLJSONSerializing> *)model {
 	NSParameterAssert(model != nil);

 	self = [super init];
 	if (self == nil) return nil;

 	_model = model;
 	_modelClass = model.class;
 	_JSONKeyPathsByPropertyKey = [[model.class JSONKeyPathsByPropertyKey] copy];

 	return self;
 }

 #pragma mark Serialization

 - (NSDictionary *)JSONDictionary {
 	NSDictionary *dictionaryValue = self.model.dictionaryValue;
 	NSMutableDictionary *JSONDictionary = [[NSMutableDictionary alloc] initWithCapacity:dictionaryValue.count];

 	[dictionaryValue enumerateKeysAndObjectsUsingBlock:^(NSString *propertyKey, id value, BOOL *stop) {
 		NSString *JSONKeyPath = [self JSONKeyPathForPropertyKey:propertyKey];
 		if (JSONKeyPath == nil) return;

 		NSValueTransformer *transformer = [self JSONTransformerForKey:propertyKey];
 		if ([transformer.class allowsReverseTransformation]) {
 			// Map NSNull -> nil for the transformer, and then back for the
 			// dictionaryValue we're going to insert into.
 			if ([value isEqual:NSNull.null]) value = nil;
 			value = [transformer reverseTransformedValue:value] ?: NSNull.null;
 		}

 		NSArray *keyPathComponents = [JSONKeyPath componentsSeparatedByString:@"."];

 		// Set up dictionaries at each step of the key path.
 		id obj = JSONDictionary;
 		for (NSString *component in keyPathComponents) {
 			if ([obj valueForKey:component] == nil) {
 				// Insert an empty mutable dictionary at this spot so that we
 				// can set the whole key path afterward.
 				[obj setValue:[NSMutableDictionary dictionary] forKey:component];
 			}

 			obj = [obj valueForKey:component];
 		}

 		[JSONDictionary setValue:value forKeyPath:JSONKeyPath];
 	}];

 	return JSONDictionary;
 }

 - (NSValueTransformer *)JSONTransformerForKey:(NSString *)key {
 	NSParameterAssert(key != nil);

 	SEL selector = MTLSelectorWithKeyPattern(key, "JSONTransformer");
 	if ([self.modelClass respondsToSelector:selector]) {
 		NSInvocation *invocation = [NSInvocation invocationWithMethodSignature:[self.modelClass methodSignatureForSelector:selector]];
 		invocation.target = self.modelClass;
 		invocation.selector = selector;
 		[invocation invoke];

 		__unsafe_unretained id result = nil;
 		[invocation getReturnValue:&result];
 		return result;
 	}

 	if ([self.modelClass respondsToSelector:@selector(JSONTransformerForKey:)]) {
 		return [self.modelClass JSONTransformerForKey:key];
 	}

 	return nil;
 }

 - (NSString *)JSONKeyPathForPropertyKey:(NSString *)key {
 	NSParameterAssert(key != nil);

 	id JSONKeyPath = self.JSONKeyPathsByPropertyKey[key];
 	if ([JSONKeyPath isEqual:NSNull.null]) return nil;

 	if (JSONKeyPath == nil) {
 		return key;
 	} else {
 		return JSONKeyPath;
 	}
 }

 @end

 @implementation MTLJSONAdapter (Deprecated)

 #pragma clang diagnostic push
 #pragma clang diagnostic ignored "-Wdeprecated-implementations"

 + (id)modelOfClass:(Class)modelClass fromJSONDictionary:(NSDictionary *)JSONDictionary {
 	return [self modelOfClass:modelClass fromJSONDictionary:JSONDictionary error:NULL];
 }

 - (id)initWithJSONDictionary:(NSDictionary *)JSONDictionary modelClass:(Class)modelClass {
 	return [self initWithJSONDictionary:JSONDictionary modelClass:modelClass error:NULL];
 }

 #pragma clang diagnostic pop

 @end
	//
	// MTLJSONAdapter.m
	// Mantle
	//
	// Created by Justin Spahr-Summers on 2013-02-12.
	// Copyright (c) 2013 GitHub. All rights reserved.
	//

	#import "MTLJSONAdapter.h"
	#import "MTLModel.h"
	#import "MTLReflection.h"

	NSString * const MTLJSONAdapterErrorDomain = @"MTLJSONAdapterErrorDomain";
	const NSInteger MTLJSONAdapterErrorNoClassFound = 2;
	const NSInteger MTLJSONAdapterErrorInvalidJSONDictionary = 3;
	const NSInteger MTLJSONAdapterErrorInvalidJSONMapping = 4;

	// An exception was thrown and caught.
	const NSInteger MTLJSONAdapterErrorExceptionThrown = 1;

	// Associated with the NSException that was caught.
	static NSString * const MTLJSONAdapterThrownExceptionErrorKey = @"MTLJSONAdapterThrownException";

	@interface MTLJSONAdapter ()

	// The MTLModel subclass being parsed, or the class of `model` if parsing has
	// completed.
	@property (nonatomic, strong, readonly) Class modelClass;

	// A cached copy of the return value of +JSONKeyPathsByPropertyKey.
	@property (nonatomic, copy, readonly) NSDictionary *JSONKeyPathsByPropertyKey;

	// Looks up the NSValueTransformer that should be used for the given key.
	//
	// key - The property key to transform from or to. This argument must not be nil.
	//
	// Returns a transformer to use, or nil to not transform the property.
	- (NSValueTransformer )JSONTransformerForKey:(NSString )key;

	@end

	@implementation MTLJSONAdapter

	#pragma mark Convenience methods

	+ (id)modelOfClass:(Class)modelClass fromJSONDictionary:(NSDictionary )JSONDictionary error:(NSError *)error {
	MTLJSONAdapter *adapter = [[self alloc] initWithJSONDictionary:JSONDictionary modelClass:modelClass error:error];
	return adapter.model;
	}

	+ (NSArray )modelsOfClass:(Class)modelClass fromJSONArray:(NSArray )JSONArray error:(NSError **)error {
	if (JSONArray == nil \|\| ![JSONArray isKindOfClass:NSArray.class]) {
	if (error != NULL) {
	NSDictionary *userInfo = @{
	NSLocalizedDescriptionKey: NSLocalizedString(@"Missing JSON array", @""),
	NSLocalizedFailureReasonErrorKey: [NSString stringWithFormat:NSLocalizedString(@"%@ could not be created because an invalid JSON array was provided: %@", @""), NSStringFromClass(modelClass), JSONArray.class],
	};
	*error = [NSError errorWithDomain:MTLJSONAdapterErrorDomain code:MTLJSONAdapterErrorInvalidJSONDictionary userInfo:userInfo];
	}
	return nil;
	}

	NSMutableArray *models = [NSMutableArray arrayWithCapacity:JSONArray.count];
	for (NSDictionary *JSONDictionary in JSONArray){
	MTLModel *model = [self modelOfClass:modelClass fromJSONDictionary:JSONDictionary error:error];

	if (model == nil) return nil;

	[models addObject:model];
	}

	return models;
	}

	+ (NSDictionary )JSONDictionaryFromModel:(MTLModel<MTLJSONSerializing> )model {
	MTLJSONAdapter *adapter = [[self alloc] initWithModel:model];
	return adapter.JSONDictionary;
	}

	+ (NSArray )JSONArrayFromModels:(NSArray )models {
	NSParameterAssert(models != nil);
	NSParameterAssert([models isKindOfClass:NSArray.class]);

	NSMutableArray *JSONArray = [NSMutableArray arrayWithCapacity:models.count];
	for (MTLModel<MTLJSONSerializing> *model in models) {
	NSDictionary *JSONDictionary = [self JSONDictionaryFromModel:model];
	if (JSONDictionary == nil) return nil;

	[JSONArray addObject:JSONDictionary];
	}

	return JSONArray;
	}

	#pragma mark Lifecycle

	- (id)init {
	NSAssert(NO, @"%@ must be initialized with a JSON dictionary or model object", self.class);
	return nil;
	}

	- (id)initWithJSONDictionary:(NSDictionary )JSONDictionary modelClass:(Class)modelClass error:(NSError *)error {
	NSParameterAssert(modelClass != nil);
	NSParameterAssert([modelClass isSubclassOfClass:MTLModel.class]);
	NSParameterAssert([modelClass conformsToProtocol:@protocol(MTLJSONSerializing)]);

	if (JSONDictionary == nil \|\| ![JSONDictionary isKindOfClass:NSDictionary.class]) {
	if (error != NULL) {
	NSDictionary *userInfo = @{
	NSLocalizedDescriptionKey: NSLocalizedString(@"Missing JSON dictionary", @""),
	NSLocalizedFailureReasonErrorKey: [NSString stringWithFormat:NSLocalizedString(@"%@ could not be created because an invalid JSON dictionary was provided: %@", @""), NSStringFromClass(modelClass), JSONDictionary.class],
	};
	*error = [NSError errorWithDomain:MTLJSONAdapterErrorDomain code:MTLJSONAdapterErrorInvalidJSONDictionary userInfo:userInfo];
	}
	return nil;
	}

	if ([modelClass respondsToSelector:@selector(classForParsingJSONDictionary:)]) {
	modelClass = [modelClass classForParsingJSONDictionary:JSONDictionary];
	if (modelClass == nil) {
	if (error != NULL) {
	NSDictionary *userInfo = @{
	NSLocalizedDescriptionKey: NSLocalizedString(@"Could not parse JSON", @""),
	NSLocalizedFailureReasonErrorKey: NSLocalizedString(@"No model class could be found to parse the JSON dictionary.", @"")
	};

	*error = [NSError errorWithDomain:MTLJSONAdapterErrorDomain code:MTLJSONAdapterErrorNoClassFound userInfo:userInfo];
	}

	return nil;
	}

	NSAssert([modelClass isSubclassOfClass:MTLModel.class], @"Class %@ returned from +classForParsingJSONDictionary: is not a subclass of MTLModel", modelClass);
	NSAssert([modelClass conformsToProtocol:@protocol(MTLJSONSerializing)], @"Class %@ returned from +classForParsingJSONDictionary: does not conform to <MTLJSONSerializing>", modelClass);
	}

	self = [super init];
	if (self == nil) return nil;

	_modelClass = modelClass;
	_JSONKeyPathsByPropertyKey = [[modelClass JSONKeyPathsByPropertyKey] copy];

	NSMutableDictionary *dictionaryValue = [[NSMutableDictionary alloc] initWithCapacity:JSONDictionary.count];

	NSSet *propertyKeys = [self.modelClass propertyKeys];

	for (NSString *JSONKeyPath in self.JSONKeyPathsByPropertyKey) {
	if ([propertyKeys containsObject:JSONKeyPath]) continue;

	if (error != NULL) {
	NSDictionary *userInfo = @{
	NSLocalizedDescriptionKey: NSLocalizedString(@"Invalid JSON mapping", nil),
	NSLocalizedFailureReasonErrorKey: [NSString stringWithFormat:NSLocalizedString(@"%1$@ could not be parsed because its JSON mapping contains illegal property keys.", nil), modelClass]
	};

	*error = [NSError errorWithDomain:MTLJSONAdapterErrorDomain code:MTLJSONAdapterErrorInvalidJSONMapping userInfo:userInfo];
	}

	return nil;
	}

	for (NSString *propertyKey in propertyKeys) {
	NSString *JSONKeyPath = [self JSONKeyPathForPropertyKey:propertyKey];
	if (JSONKeyPath == nil) continue;

	id value;
	@try {
	value = [JSONDictionary valueForKeyPath:JSONKeyPath];
	} @catch (NSException *ex) {
	if (error != NULL) {
	NSDictionary *userInfo = @{
	NSLocalizedDescriptionKey: NSLocalizedString(@"Invalid JSON dictionary", nil),
	NSLocalizedFailureReasonErrorKey: [NSString stringWithFormat:NSLocalizedString(@"%1$@ could not be parsed because an invalid JSON dictionary was provided for key path \"%2$@\"", nil), modelClass, JSONKeyPath],
	MTLJSONAdapterThrownExceptionErrorKey: ex
	};

	*error = [NSError errorWithDomain:MTLJSONAdapterErrorDomain code:MTLJSONAdapterErrorInvalidJSONDictionary userInfo:userInfo];
	}

	return nil;
	}

	if (value == nil) continue;

	@try {
	NSValueTransformer *transformer = [self JSONTransformerForKey:propertyKey];
	if (transformer != nil) {
	// Map NSNull -> nil for the transformer, and then back for the
	// dictionary we're going to insert into.
	if ([value isEqual:NSNull.null]) value = nil;
	value = [transformer transformedValue:value] ?: NSNull.null;
	}

	dictionaryValue[propertyKey] = value;
	} @catch (NSException *ex) {
	NSLog(@"*** Caught exception %@ parsing JSON key path \"%@\" from: %@", ex, JSONKeyPath, JSONDictionary);

	// Fail fast in Debug builds.
	#if DEBUG
	@throw ex;
	#else
	if (error != NULL) {
	NSDictionary *userInfo = @{
	NSLocalizedDescriptionKey: ex.description,
	NSLocalizedFailureReasonErrorKey: ex.reason,
	MTLJSONAdapterThrownExceptionErrorKey: ex
	};

	*error = [NSError errorWithDomain:MTLJSONAdapterErrorDomain code:MTLJSONAdapterErrorExceptionThrown userInfo:userInfo];
	}

	return nil;
	#endif
	}
	}

	_model = [self.modelClass modelWithDictionary:dictionaryValue error:error];
	if (_model == nil) return nil;

	return self;
	}

	- (id)initWithModel:(MTLModel<MTLJSONSerializing> *)model {
	NSParameterAssert(model != nil);

	self = [super init];
	if (self == nil) return nil;

	_model = model;
	_modelClass = model.class;
	_JSONKeyPathsByPropertyKey = [[model.class JSONKeyPathsByPropertyKey] copy];

	return self;
	}

	#pragma mark Serialization

	- (NSDictionary *)JSONDictionary {
	NSDictionary *dictionaryValue = self.model.dictionaryValue;
	NSMutableDictionary *JSONDictionary = [[NSMutableDictionary alloc] initWithCapacity:dictionaryValue.count];

	[dictionaryValue enumerateKeysAndObjectsUsingBlock:^(NSString propertyKey, id value, BOOL stop) {
	NSString *JSONKeyPath = [self JSONKeyPathForPropertyKey:propertyKey];
	if (JSONKeyPath == nil) return;

	NSValueTransformer *transformer = [self JSONTransformerForKey:propertyKey];
	if ([transformer.class allowsReverseTransformation]) {
	// Map NSNull -> nil for the transformer, and then back for the
	// dictionaryValue we're going to insert into.
	if ([value isEqual:NSNull.null]) value = nil;
	value = [transformer reverseTransformedValue:value] ?: NSNull.null;
	}

	NSArray *keyPathComponents = [JSONKeyPath componentsSeparatedByString:@"."];

	// Set up dictionaries at each step of the key path.
	id obj = JSONDictionary;
	for (NSString *component in keyPathComponents) {
	if ([obj valueForKey:component] == nil) {
	// Insert an empty mutable dictionary at this spot so that we
	// can set the whole key path afterward.
	[obj setValue:[NSMutableDictionary dictionary] forKey:component];
	}

	obj = [obj valueForKey:component];
	}

	[JSONDictionary setValue:value forKeyPath:JSONKeyPath];
	}];

	return JSONDictionary;
	}

	- (NSValueTransformer )JSONTransformerForKey:(NSString )key {
	NSParameterAssert(key != nil);

	SEL selector = MTLSelectorWithKeyPattern(key, "JSONTransformer");
	if ([self.modelClass respondsToSelector:selector]) {
	NSInvocation *invocation = [NSInvocation invocationWithMethodSignature:[self.modelClass methodSignatureForSelector:selector]];
	invocation.target = self.modelClass;
	invocation.selector = selector;
	[invocation invoke];

	__unsafe_unretained id result = nil;
	[invocation getReturnValue:&result];
	return result;
	}

	if ([self.modelClass respondsToSelector:@selector(JSONTransformerForKey:)]) {
	return [self.modelClass JSONTransformerForKey:key];
	}

	return nil;
	}

	- (NSString )JSONKeyPathForPropertyKey:(NSString )key {
	NSParameterAssert(key != nil);

	id JSONKeyPath = self.JSONKeyPathsByPropertyKey[key];
	if ([JSONKeyPath isEqual:NSNull.null]) return nil;

	if (JSONKeyPath == nil) {
	return key;
	} else {
	return JSONKeyPath;
	}
	}

	@end

	@implementation MTLJSONAdapter (Deprecated)

	#pragma clang diagnostic push
	#pragma clang diagnostic ignored "-Wdeprecated-implementations"

	+ (id)modelOfClass:(Class)modelClass fromJSONDictionary:(NSDictionary *)JSONDictionary {
	return [self modelOfClass:modelClass fromJSONDictionary:JSONDictionary error:NULL];
	}

	- (id)initWithJSONDictionary:(NSDictionary *)JSONDictionary modelClass:(Class)modelClass {
	return [self initWithJSONDictionary:JSONDictionary modelClass:modelClass error:NULL];
	}

	#pragma clang diagnostic pop

	@end