Add new custom value transformers.

Mobile Buy SDK/Mobile Buy SDK/Additions/NSEntityDescription+BUYAdditions.h

+//
+//  NSEntityDescription+BUYAdditions.h
+//  Mobile Buy SDK
+//
+//  Created by Shopify.
+//  Copyright (c) 2015 Shopify Inc. All rights reserved.
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in
+//  all copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+//  THE SOFTWARE.
+//
+
+#import <CoreData/CoreData.h>
+
+@protocol BUYObject;
+
+@interface NSEntityDescription (BUYAdditions)
+
+/**
+ * A dictionary of @{ NSString : NSPropertyDescription } where the keys are property names.
+ * By default, returns all attributes (instances of NSAttributeDescription) and relationships (NSRelationshipDescription).
+ */
+@property (nonatomic, readonly, getter=buy_JSONEncodedProperties) NSDictionary *JSONEncodedProperties;
+
+/**
+ * Returns the custom subclass used for instances of this entity.
+ */
+@property (nonatomic, readonly, getter=buy_managedObjectClass) Class managedObjectClass;
+
+/**
+ * Signifies whether this entity is private to the app (not used by the endpoint).
+ */
+- (BOOL)buy_isPrivate;
+
+/**
+ * Generate JSON, recursively, from the provided model object.
+ */
+- (NSDictionary *)buy_JSONForObject:(id<BUYObject>)object;
+
+/**
+ * Generate JSON, recursively, for each model in the provided array.
+ */
+- (NSArray *)buy_JSONForArray:(NSArray<NSObject<BUYObject> *> *)array;
+
+/**
+ * Update the properties of the given model object, and child objects, using the given JSON dictionary.
+ */
+- (void)buy_updateObject:(id<BUYObject>)object withJSON:(NSDictionary *)JSON;
+
+@end

Mobile Buy SDK/Mobile Buy SDK/Additions/NSEntityDescription+BUYAdditions.m

+//
+//  NSEntityDescription+BUYAdditions.m
+//  Mobile Buy SDK
+//
+//  Created by Shopify.
+//  Copyright (c) 2015 Shopify Inc. All rights reserved.
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in
+//  all copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+//  THE SOFTWARE.
+//
+
+#import "NSEntityDescription+BUYAdditions.h"
+
+#import "BUYModelManagerProtocol.h"
+#import "BUYObjectProtocol.h"
+
+#import "NSDictionary+BUYAdditions.h"
+#import "NSPropertyDescription+BUYAdditions.h"
+#import "NSString+BUYAdditions.h"
+
+@interface NSEntityDescription ()
+
+/**
+ * Returns a block that maps JSON keys into a property name.
+ * Used when updating model objects from JSON.
+ */
+@property (nonatomic, readonly, getter=buy_JSONKeyEncodingMap) BUYStringMap JSONKeyEncodingMap;
+
+/**
+ * Returns a block that maps property names into JSON keys.
+ * Used when generating JSON data from model objects.
+ */
+@property (nonatomic, readonly, getter=buy_JSONKeyDecodingMap) BUYStringMap JSONKeyDecodingMap;
+
+@end
+
+@implementation NSEntityDescription (BUYAdditions)
+
+#pragma mark - Derived Properties
+
+- (Class)buy_managedObjectClass
+{
+	return NSClassFromString(self.managedObjectClassName);
+}
+
+- (BOOL)buy_isPrivate
+{
+	return [self.userInfo[@"private"] boolValue];
+}
+
+#pragma mark - Property Lookup Conveniences
+
+- (NSDictionary *)buy_JSONEncodedProperties
+{
+	NSMutableDictionary *properties = [NSMutableDictionary dictionaryWithDictionary:[self attributesByName]];
+	[properties addEntriesFromDictionary:[self relationshipsByName]];
+	return properties;
+}
+
+- (NSPropertyDescription *)buy_propertyWithName:(NSString *)name
+{
+	return self.propertiesByName[name];
+}
+
+#pragma mark - JSON <-> Property key mapping
+
+// TODO: profile and optimize if necessary
+
+- (BUYStringMap)buy_JSONKeyEncodingMap
+{
+	NSDictionary *mapping = [self buy_PropertyNameMapping];
+	return ^(NSString *name) {
+		return mapping[name] ?: [name buy_snakeCaseString];
+	};
+}
+
+- (BUYStringMap)buy_JSONKeyDecodingMap
+{
+	NSDictionary *mapping = [self buy_JSONKeyMapping];
+	return ^(NSString *key) {
+		return mapping[key] ?: [key buy_camelCaseString];
+	};
+}
+
+#pragma mark - Property lookup
+
++ (NSDictionary *)buy_defaultPropertyNameMapping
+{
+	return @{ @"identifier" : @"id" };
+}
+
+// json key -> property name
+- (NSDictionary *)buy_JSONKeyMapping
+{
+	return [[self buy_PropertyNameMapping] buy_reverseDictionary];
+}
+
+// property name -> json key
+- (NSDictionary *)buy_PropertyNameMapping
+{
+	return [self.propertiesByName buy_dictionaryByMappingValuesWithBlock:^(NSPropertyDescription *property) {
+		return [self buy_JSONKeyForPropertyName:property.name];
+	}];
+}
+
+- (NSString *)buy_JSONKeyForPropertyName:(NSString *)name
+{
+	return [self buy_propertyWithName:name].JSONPropertyKey ?: [NSEntityDescription buy_defaultPropertyNameMapping][name];
+}
+
+#pragma mark - Object-Plist transformation
+
+- (NSDictionary *)buy_JSONForObject:(NSObject<BUYObject> *)object
+{
+	NSAssert([self isEqual:[object entity]], @"%@ entity cannot decode %@ objects", self.name, [object entity].name);
+	
+	// The encoding map is a block which converts property names into JSON keys.
+	BUYStringMap encodingMap = self.JSONKeyEncodingMap;
+	
+	NSMutableDictionary *results = [NSMutableDictionary dictionary];
+	[object.JSONEncodedProperties enumerateKeysAndObjectsUsingBlock:^(NSString *propertyName, NSPropertyDescription *property, BOOL *stop) {
+		id value = [object valueForKey:propertyName];
+		if (value) {
+			// Each property is responsible for knowing how to generate JSON for its value
+			// Some properties do not encode themselves in JSON, so we mut check for nil
+			id JSONValue = [property buy_JSONForValue:value];
+			if (JSONValue) {
+				NSString *JSONKey = encodingMap(propertyName) ?: propertyName;
+				results[JSONKey] = JSONValue;
+			}
+		}
+	}];
+	
+	return results;
+}
+
+- (NSArray *)buy_JSONForArray:(NSArray<NSObject<BUYObject> *> *)array
+{
+	return [array buy_map:^(NSObject<BUYObject> *object) {
+		return [self buy_JSONForObject:object];
+	}];
+}
+
+- (void)buy_updateObject:(NSObject<BUYObject> *)object withJSON:(NSDictionary *)JSON
+{
+	NSAssert([self isEqual:[object entity]], @"%@ entity cannot decode %@ objects", self.name, [object entity].name);
+	
+	NSDictionary *properties = self.propertiesByName;
+	// The decoding map is a block which converts the key in the JSON into a property name.
+	BUYStringMap decodingMap = self.JSONKeyDecodingMap;
+	
+	// Iterate through the JSON, and generate the native value using the property object.
+	NSMutableDictionary *results = [NSMutableDictionary dictionary];
+	[JSON enumerateKeysAndObjectsUsingBlock:^(NSString *key, id value, BOOL * stop) {
+		NSString *propertyName = decodingMap(key) ?: key;
+		NSPropertyDescription *property = properties[propertyName];
+		// Each property is responsible for knowing how to parse JSON for its value
+		results[propertyName] = [property buy_valueForJSON:value object:object];
+	}];
+	
+	[object setValuesForKeysWithDictionary:results];
+}
+
+@end

Mobile Buy SDK/Mobile Buy SDK/Additions/NSPropertyDescription+BUYAdditions.h

+//
+//  NSPropertyDescription+BUYAdditions.h
+//  Mobile Buy SDK
+//
+//  Created by Shopify.
+//  Copyright (c) 2015 Shopify Inc. All rights reserved.
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in
+//  all copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+//  THE SOFTWARE.
+//
+
+#import <CoreData/CoreData.h>
+
+@class BUYModelManager;
+@protocol BUYObject;
+
+// property user info keys
+extern NSString * const BUYJSONValueTransformerUserInfoKey; // = @"JSONValueTransformer";
+extern NSString * const BUYJSONPropertyKeyUserInfoKey;      // = @"JSONPropertyKey";
+
+@interface NSPropertyDescription (BUYAdditions)
+
+/**
+ * The name of a value transformer used to convert to JSON values and back.
+ * Uses the value specified in the property's user info dictionary under the "JSONValueTransformer" key.
+ *
+ * Currently only two transformers are supported: "BUYPublicationsDate" and "BUYShippingRateDate".
+ * Currently, only attributes (instances of NSAttributeDescription) use value transformers.
+ */
+@property (nonatomic, readonly, getter=buy_JSONValueTransformerName) NSString *JSONValueTransformerName;
+
+/**
+ * The value transformer corresponding to the JSONValueTransformerName. If no name is specified,
+ * the value is not changed.
+ */
+@property (nonatomic, readonly, getter=buy_JSONValueTransformer) NSValueTransformer *JSONValueTransformer;
+
+/**
+ * The name of the key to use for the property, instead of its name, when generating JSON. Requires
+ * adding an entry in the Property userInfo, in the Core Data model file, with the key "JSONPropertyKey".
+ */
+@property (nonatomic, readonly, getter=buy_JSONPropertyKey) NSString *JSONPropertyKey;
+
+/**
+ * Convert the provided JSON into the appropriate data type, either simple values or model objects.
+ * For relationships, uses the destinationEntity to recursively fetch or create related objects as needed.
+ */
+- (id)buy_valueForJSON:(id)JSON object:(id<BUYObject>)object;
+
+/**
+ * Convert the provided object, a value corresponding to the property on the parent object.
+ *
+ * For relationships, related object data is generated according to the following rules:
+ * - if the "JSONPropertyKey" is set in the user info dictionary, and it ends in "_id" (or "_ids")
+ *   then encode the related object(s) using only their identifier(s)
+ * - if the inverse relationship delete rule is "Cascade", or its entity is marked private,
+ *   or the relationship is many-to-many, do not encode the object for this relationship
+ *   (it is inferred that the related object owns this object; this avoids a loop in the encoding)
+ * - otherwise, encode the full JSON representation of the related object(s)
+ */
+- (id)buy_JSONForValue:(id)value;
+
+@end
+
+@interface NSRelationshipDescription (BUYAdditions)
+
+/**
+ * Used during JSON transformation. If the value is YES, parsed JSON is expected to be a number
+ * representing an object identifier, which will be resolved by fetching from the persistent store.
+ * Likewise, generated JSON will include identifiers in place of full objects.
+ */
+@property (nonatomic, readonly, getter=buy_encodesIdInJSON) BOOL encodesIdInJSON;
+
+/**
+ * YES if the delete rule is not Cascading and the entity is not private.
+ */
+@property (nonatomic, readonly, getter=buy_allowsInverseEncoding) BOOL allowsInverseEncoding;
+
+/**
+ * YES if this relationship and its inverse are both toMany
+ */
+@property (nonatomic, readonly, getter=buy_isManyToMany) BOOL manyToMany;
+
+@end

Mobile Buy SDK/Mobile Buy SDK/Additions/NSPropertyDescription+BUYAdditions.m

+//
+//  NSPropertyDescription+BUYAdditions.m
+//  Mobile Buy SDK
+//
+//  Created by Shopify.
+//  Copyright (c) 2015 Shopify Inc. All rights reserved.
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in
+//  all copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+//  THE SOFTWARE.
+//
+
+#import "NSPropertyDescription+BUYAdditions.h"
+
+#import "BUYModelManagerProtocol.h"
+#import "BUYObjectProtocol.h"
+#import "NSDecimalNumber+BUYAdditions.h"
+#import "NSArray+BUYAdditions.h"
+#import "NSException+BUYAdditions.h"
+#import "NSEntityDescription+BUYAdditions.h"
+
+#import "BUYDateTransformer.h"
+#import "BUYDecimalNumberTransformer.h"
+#import "BUYIdentityTransformer.h"
+#import "BUYURLTransformer.h"
+
+
+// User Info Keys
+NSString * const BUYJSONValueTransformerUserInfoKey = @"JSONValueTransformer";
+NSString * const BUYJSONPropertyKeyUserInfoKey = @"JSONPropertyKey";
+
+// This is defined by mogenerator
+static NSString * const BUYAttributeValueClassNameKey = @"attributeValueClassName";
+
+#pragma mark -
+
+@interface NSObject (BUYValueTransforming)
+- (BOOL)buy_isValidObject;
++ (NSString *)buy_JSONValueTransformerName;
+@end
+
+#pragma mark -
+
+@implementation NSPropertyDescription (BUYAdditions)
+
+- (NSString *)buy_JSONValueTransformerName
+{
+	static dispatch_once_t onceToken;
+	dispatch_once(&onceToken, ^{
+		// default transformer
+		[NSValueTransformer setValueTransformer:[[BUYIdentityTransformer alloc] init] forName:BUYIdentityTransformerName];
+		
+		// attribute type transformers
+		[NSValueTransformer setValueTransformer:[[BUYDecimalNumberTransformer alloc] init] forName:BUYDecimalNumberTransformerName];
+		
+		// value type transformers
+		[NSValueTransformer setValueTransformer:[[BUYURLTransformer alloc] init] forName:BUYURLTransformerName];
+	});
+	return self.userInfo[BUYJSONValueTransformerUserInfoKey];
+}
+
+- (NSString *)buy_JSONPropertyKey
+{
+	return self.userInfo[BUYJSONPropertyKeyUserInfoKey];
+}
+
+- (NSValueTransformer *)buy_JSONValueTransformer
+{
+	return [NSValueTransformer valueTransformerForName:self.JSONValueTransformerName];
+}
+
+- (id)buy_valueForJSON:(id)JSON object:(id<BUYObject>)object
+{
+	@throw BUYAbstractMethod();
+}
+
+- (id)buy_JSONForValue:(id)object
+{
+	@throw BUYAbstractMethod();
+}
+
+@end
+
+#pragma mark -
+
+static NSString *JSONValueTransformerNameForAttributeType(NSAttributeType type)
+{
+	NSString *name = nil;
+	switch (type) {
+		case NSDateAttributeType:
+			name = BUYDateTransformerName;
+			break;
+			
+		case NSDecimalAttributeType:
+			name = BUYDecimalNumberTransformerName;
+			break;
+			
+		default:
+			break;
+	}
+	return name;
+}
+
+@implementation NSAttributeDescription (BUYAdditions)
+
+- (NSString *)buy_attributeValueClassName
+{
+	return self.userInfo[BUYAttributeValueClassNameKey];
+}
+
+- (Class)buy_attributeValueClass
+{
+	return NSClassFromString([self buy_attributeValueClassName]);
+}
+
+- (NSString *)buy_JSONValueTransformerName
+{
+	NSString *name = [super buy_JSONValueTransformerName];
+	if (name == nil) {
+		name = JSONValueTransformerNameForAttributeType(self.attributeType);
+	}
+	if (name == nil) {
+		name = [[self buy_attributeValueClass] buy_JSONValueTransformerName];
+	}
+	if (name == nil) {
+		name = BUYIdentityTransformerName;
+	}
+	return name;
+}
+
+- (id)buy_valueForJSON:(id)JSON object:(id<BUYObject>)object
+{
+	// An attribute's value is determined by the specified transformer.
+	// An Identity transform returns the same value. `nil` is converted into `NSNull`.
+	id transformedValue = [JSON buy_isValidObject] ? [self.JSONValueTransformer reverseTransformedValue:JSON] : [NSNull null];
+	return transformedValue ?: [NSNull null];
+}
+
+- (id)buy_JSONForValue:(id)object
+{
+	// An attribute's JSON is determined by the specified transformer.
+	// An identify transform returns the same value.
+	return [self.JSONValueTransformer transformedValue:object];
+}
+
+@end
+
+#pragma mark -
+
+@implementation NSRelationshipDescription (BUYAdditions)
+
+- (NSString *)encodesIdSuffix
+{
+	return (self.isToMany ? @"_ids" : @"_id");
+}
+
+- (BOOL)buy_encodesIdInJSON
+{
+	return [self.JSONPropertyKey hasSuffix:[self encodesIdSuffix]];
+}
+
+- (id)buy_transformArray:(NSArray<id<BUYObject>> *)array
+{
+	return self.isOrdered ? [NSOrderedSet orderedSetWithArray:array] : [NSSet setWithArray:array];
+}
+
+- (id)buy_objectForJSON:(id)JSON modelManager:(id<BUYModelManager>)modelManager
+{
+	NSString *entityName = self.destinationEntity.name;
+	// If we are expecting an object `id` the object should already exist.
+	// Otherwise let the object context decide how to resolve the object and update it.
+	if (self.encodesIdInJSON) {
+		return [modelManager buy_objectWithEntityName:entityName identifier:JSON];
+	}
+	else {
+		return [modelManager buy_objectWithEntityName:entityName JSONDictionary:JSON];
+	}
+}
+
+- (id)buy_collectionForJSON:(NSArray *)JSON object:(id<BUYObject>)object
+{
+	NSString *entityName = self.destinationEntity.name;
+	NSArray<id<BUYObject>> *array;
+	
+	// If we are expecting an array of object `ids`, the objects should already exist.
+	// Otherwise, let the object context decide how to resolve the objects and update them.
+	// If device caching is not provided, this will return nothing.
+	if (self.encodesIdInJSON) {
+		array = [object.modelManager buy_objectsWithEntityName:entityName identifiers:JSON];
+	}
+	else {
+		array = [object.modelManager buy_objectsWithEntityName:entityName JSONArray:JSON];
+	}
+	
+	// Transform the array to the correct container type (`NSSet` or `NSOrderedSet`).
+	return [self buy_transformArray:array];
+}
+
+
+- (id)buy_valueForJSON:(id)JSON object:(id<BUYObject>)object
+{
+	// A relationship's value is provided by the object context.
+	// The logic for decoding JSON is slightly different for to-one and to-many relationships.
+	
+	// NOTE: by default, without a caching system, inverse relationships are not supported.
+	if (JSON && ![JSON isEqual:[NSNull null]]) {
+		if (self.isToMany) {
+			return [self buy_collectionForJSON:JSON object:object];
+		}
+		else {
+			return [self buy_objectForJSON:JSON modelManager:object.modelManager];
+		}
+	}
+	else {
+		return nil;
+	}
+}
+
+- (id)buy_JSONForValue:(id)value
+{
+	return self.toMany ? [self buy_JSONForCollection:value] : [self buy_JSONForObject:value];
+}
+
+- (NSArray *)buy_JSONForCollection:(id)collection
+{
+	if (self.manyToMany) {
+		return nil;
+	}
+	
+	NSArray *array = [self buy_arrayForCollection:collection];
+	return self.encodesIdInJSON ? [array valueForKey:@"identifier"] : [self.destinationEntity buy_JSONForArray:array];
+}
+
+- (NSArray *)buy_arrayForCollection:(id)collection
+{
+	return self.ordered ? [collection array] : [collection allObjects];
+}
+
+- (id)buy_JSONForObject:(NSObject<BUYObject> *)object
+{
+	// JSON generation for a relationship depends on the rules defined in the model.
+	// The model can explicitly specify using an `id` encoding.
+	// Alternately, if the relationship is compatible, encode the entire object.
+	// We do not encode related objects unless three conditions are satisfied:
+	// 1. the relationship is not many-to-many
+	// 2. the inverse relationship is not an ownership relationship
+	//    (this is inferred from the `NSCascadeDeleteRule` used by owning objects)
+	// 3. the relationship is to a "private" entity (not known to the API)
+	if (self.encodesIdInJSON) {
+		return [[object valueForKey:self.name] identifier];
+	}
+	else if (!self.inverseRelationship || self.inverseRelationship.allowsInverseEncoding) {
+		return [self.destinationEntity buy_JSONForObject:object];
+	}
+	else {
+		return nil;
+	}
+}
+
+- (BOOL)buy_isManyToMany
+{
+	return self.toMany && self.inverseRelationship.toMany;
+}
+
+- (BOOL)buy_allowsInverseEncoding
+{
+	return self.deleteRule != NSCascadeDeleteRule && ![self.entity buy_isPrivate];
+}
+
+@end
+
+#pragma mark -
+
+@implementation NSFetchedPropertyDescription (BUYAdditions)
+
+- (id)buy_valueForJSON:(id)JSON object:(id<BUYObject>)object
+{
+	return nil;
+}
+
+- (id)buy_reverseTransformedJSONValue:(id)value
+{
+	return nil;
+}
+
+@end
+
+#pragma mark -
+
+// We could be really clever here and use an algorithm for string transformation
+// but it's not worth it right now.
+@implementation NSObject (BUYValueTransforming)
+
++ (NSString *)buy_JSONValueTransformerName
+{
+	return BUYIdentityTransformerName;
+}
+
+- (BOOL)buy_isValidObject
+{
+	return YES;
+}
+
+@end
+
+@implementation NSNull (BUYValueTransforming)
+
+- (BOOL)buy_isValidObject
+{
+	return NO;
+}
+
+@end
+
+@implementation NSURL (BUYValueTransforming)
+
++ (NSString *)buy_JSONValueTransformerName
+{
+	return BUYURLTransformerName;
+}
+
+@end

Mobile Buy SDK/Mobile Buy SDK/Models/BUYModelManagerProtocol.h

+//
+//  BUYModelManagerProtocol.h
+//  Mobile Buy SDK
+//
+//  Created by Shopify.
+//  Copyright (c) 2015 Shopify Inc. All rights reserved.
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in
+//  all copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+//  THE SOFTWARE.
+//
+
+#import <CoreData/CoreData.h>
+
+/**
+ * A protocol for defining an object that can store and retrieve model objects from a data store or other cache.
+ */
+@protocol BUYModelManager <NSObject>
+
+/**
+ *  Returns an entity given its name.
+ *
+ *  @param entityName Name of the entity from the Core Data managed object model.
+ *
+ *  @return The entity description matching the name.
+ */
+- (NSEntityDescription *)buy_entityWithName:(NSString *)entityName;
+
+/**
+ * If the JSON contains a key representing the unique identifier, and there is an existing cached object that matches that identifier,
+ * then that object will be updated with the remaining entries in the JSON. If no such object exists, a new object is created, and
+ * sent -updateWithJSON:.
+ *
+ *  @param entityName Name of the entity from the Core Data managed object model.
+ *  @param JSON       The JSON representing the object.
+ *
+ *  @return A new or existing model object.
+ */
+- (id<BUYObject>)buy_objectWithEntityName:(NSString *)entityName JSONDictionary:(NSDictionary *)JSON;
+- (NSArray<id<BUYObject>> *)buy_objectsWithEntityName:(NSString *)entityName JSONArray:(NSArray *)JSON;
+
+/**
+ * Cache-based model managers may resolve objects based on their identifier. The alternative is to return nil.
+ * Only supported by models whose entity declares an "identifier" attribute.
+ *
+ *  @param entityName Name of the entity from the Core Data managed object model.
+ *  @param identifier A shopify object identifier of an existing object in the local data cache.
+ *
+ *  @return An object from the cache matching the provided identifier, or nil if no matching object is found.
+ */
+- (id<BUYObject>)buy_objectWithEntityName:(NSString *)entityName identifier:(NSNumber *)identifier;
+
+/**
+ *  Find all the objects in the cache matching the provided identifiers.
+ *
+ *  @param entityName  Name of the entity from the Core Data managed object model.
+ *  @param identifiers An array of Shopify object identifiers.
+ *
+ *  @return An array of objects from the cache matching the provided identifiers, if any.
+ */
+- (NSArray<id<BUYObject>> *)buy_objectsWithEntityName:(NSString *)entityName identifiers:(NSArray *)identifiers;
+
+/**
+ * If there is a local cache available, and the object is cached, it is flushed from the cache. Depending on the type of
+ * caching in use (if any), the provided object may no longer be valid, and references should be reset. If the cache
+ * supports stand-alone objects, and the object is modified or passed into the SDK, it could be re-inserted into the cache.
+ *
+ * If Core Data is used for local caching, purging is equivalent to deletion. (see -deleteObject[WithIdentifier]:error:)
+ *
+ * If the object is not in the cache (or there is no cache), does nothing.
+ *
+ *  @param object An existing model object.
+ *  @param error  A pointer to an error. May be NULL.
+ *
+ *  @return YES if the object was successfully removed from the cache. NO if there was an error.
+ */
+- (BOOL)buy_purgeObject:(id<BUYObject>)object error:(NSError **)error;
+
+/**
+ * Update the cached version of the object given the current state of the object.
+ *
+ *  @param object An existing model object.
+ */
+- (void)buy_refreshCacheForObject:(id<BUYObject>)object;
+
+/**
+ *
+ *  @param entityName Name of the entity from the Core Data managed object model.
+ *  @param predicate  An NSPredicate that identifies objects that should be deleted from the cache.
+ *
+ *  @return YES if the purge was successful. NO if there was a problem.
+ */
+- (BOOL)buy_purgeObjectsWithEntityName:(NSString *)entityName matchingPredicate:(NSPredicate *)predicate;
+
+@end

Mobile Buy SDK/Mobile Buy SDK/Models/BUYObjectProtocol.h

+//
+//  BUYObjectProtocol.h
+//  Mobile Buy SDK
+//
+//  Created by Shopify.
+//  Copyright (c) 2015 Shopify Inc. All rights reserved.
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in
+//  all copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+//  THE SOFTWARE.
+//
+
+#import <Foundation/Foundation.h>
+
+@protocol BUYModelManager;
+
+/**
+ * The BUYObject protocol is adopted by the common superclasses of both persistent and transient model classes.
+ *
+ */
+@protocol BUYObject <NSObject>
+
+@property (nonatomic, readonly, weak) id<BUYModelManager> modelManager;
+
+/**
+ * Transient model objects need an entity for introspection.
+ */
+@property (nonatomic, readonly, weak) NSEntityDescription *entity;
+
+/**
+ * A dictionary of @{ NSString : NSPropertyDescription } where the keys are property names.
+ * By default, returns the same value defined on NSEntityDescription (from BUYAdditions).
+ */
+@property (nonatomic, readonly) NSDictionary *JSONEncodedProperties;
+
+/**
+ * Convenience static property overridden by auto-generated model files.
+ */
++ (NSString *)entityName;
+
+/**
+ * A derived property used to generate or apply JSON data. Values are calculated, recursively, automatically.
+ */
+@property (nonatomic, strong) NSDictionary *JSONDictionary;
+
+/**
+ * A predicate composed of values from the JSON. For objects that do not have an "identifier"/"id" property.
+ */
++ (NSPredicate *)fetchPredicateWithJSON:(NSDictionary *)JSONDictionary;
+
+/**
+ * Persistent classes return YES; transient classes return NO.
+ */
++ (BOOL)isPersistentClass;
+
+/**
+ * Conforming classes should override to specify whether to use dirty tracking to restrict generated JSON to only changed values.
+ */
++ (BOOL)tracksDirtyProperties;
+
+/**
+ * Use the values in the given dictionary to update properties.
+ */
+- (void)updateWithJSONDictionary:(NSDictionary *)dictionary;
+
+@optional
+
+- (instancetype)initWithModelManager:(id<BUYModelManager>)modelManager JSONDictionary:(NSDictionary *)dictionary;
+
+@end

Mobile Buy SDK/Mobile Buy SDK/Value Transformers/BUYDateTransformer.h

+//
+//  BUYDateTransformer.h
+//  Mobile Buy SDK
+//
+//  Created by Shopify.
+//  Copyright (c) 2015 Shopify Inc. All rights reserved.
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in
+//  all copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+//  THE SOFTWARE.
+//
+
+#import <Foundation/Foundation.h>
+
+extern NSString * const BUYDateTransformerName; // = @"BUYDate";
+
+/**
+ * Transforms a date object into a string and back using the provided format string.
+ */
+@interface BUYDateTransformer : NSValueTransformer
++ (instancetype)dateTransformerWithFormat:(NSString *)format;
+@end

Mobile Buy SDK/Mobile Buy SDK/Value Transformers/BUYDateTransformer.m

+//
+//  BUYDateTransformer.m
+//  Mobile Buy SDK
+//
+//  Created by Shopify.
+//  Copyright (c) 2015 Shopify Inc. All rights reserved.
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in
+//  all copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+//  THE SOFTWARE.
+//
+
+#import "BUYDateTransformer.h"
+
+NSString * const BUYDateTransformerName = @"BUYDate";
+
+@interface BUYDateTransformer ()
+@property (nonatomic, strong) NSDateFormatter *dateFormatter;
+@end
+
+@implementation BUYDateTransformer
+
+- (instancetype)initWithDateFormatter:(NSDateFormatter *)formatter
+{
+	self = [super init];
+	if (self) {
+		self.dateFormatter = formatter;
+	}
+	return self;
+}
+
+- (NSString *)transformedValue:(NSDate *)value
+{
+	return [self.dateFormatter stringFromDate:value];
+}
+
+- (NSDate *)reverseTransformedValue:(NSString *)value
+{
+	return [self.dateFormatter dateFromString:value];
+}
+
++ (instancetype)dateTransformerWithFormat:(NSString *)format
+{
+	NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
+	[formatter setDateFormat:format];
+	return [[self alloc] initWithDateFormatter:formatter];
+}
+
++ (BOOL)allowsReverseTransformation
+{
+	return YES;
+}
+
++ (Class)transformedValueClass
+{
+	return [NSString class];
+}
+
+@end

Mobile Buy SDK/Mobile Buy SDK/Value Transformers/BUYDecimalNumberTransformer.h

+//
+//  BUYDecimalNumberTransformer.h
+//  Mobile Buy SDK
+//
+//  Created by Shopify.
+//  Copyright (c) 2015 Shopify Inc. All rights reserved.
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in
+//  all copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+//  THE SOFTWARE.
+//
+
+#import <Foundation/Foundation.h>
+
+extern NSString * const BUYDecimalNumberTransformerName; // = @"BUYDecimalNumber";
+
+/**
+ * Transforms a decimal number object into a string and back.
+ */
+@interface BUYDecimalNumberTransformer : NSValueTransformer
+@end

Mobile Buy SDK/Mobile Buy SDK/Value Transformers/BUYDecimalNumberTransformer.m

+//
+//  BUYDecimalNumberTransformer.m
+//  Mobile Buy SDK
+//
+//  Created by Shopify.
+//  Copyright (c) 2015 Shopify Inc. All rights reserved.
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in
+//  all copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+//  THE SOFTWARE.
+//
+
+#import "BUYDecimalNumberTransformer.h"
+#import "NSDecimalNumber+BUYAdditions.h"
+
+NSString * const BUYDecimalNumberTransformerName = @"BUYDecimalNumber";
+
+@implementation BUYDecimalNumberTransformer
+
++ (Class)transformedValueClass
+{
+	return [NSString class];
+}
+
++ (BOOL)allowsReverseTransformation
+{
+	return YES;
+}
+
+- (id)transformedValue:(NSDecimalNumber *)value
+{
+	return [value stringValue];
+}
+
+- (id)reverseTransformedValue:(id)value
+{
+	return [NSDecimalNumber buy_decimalNumberFromJSON:value];
+}
+
+@end

Mobile Buy SDK/Mobile Buy SDK/Value Transformers/BUYDeliveryRangeTransformer.h

+//
+//  BUYDeliveryRangeTransformer.h
+//  Mobile Buy SDK
+//
+//  Created by Shopify.
+//  Copyright (c) 2015 Shopify Inc. All rights reserved.
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in
+//  all copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+//  THE SOFTWARE.
+//
+
+#import <Foundation/Foundation.h>
+
+extern NSString * const BUYShippingRateDateTransformerName; // = @"BUYShippingRateDate";
+extern NSString * const BUYShippingRateDateFormat; // = @"yyyy-MM-dd'T'HH:mm:ss.SSSZ";
+
+@interface BUYDeliveryRangeTransformer : NSValueTransformer
+
+@end

Mobile Buy SDK/Mobile Buy SDK/Value Transformers/BUYDeliveryRangeTransformer.m

+//
+//  BUYDeliveryRangeTransformer.m
+//  Mobile Buy SDK
+//
+//  Created by Shopify.
+//  Copyright (c) 2015 Shopify Inc. All rights reserved.
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in
+//  all copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+//  THE SOFTWARE.
+//
+
+#import "BUYDeliveryRangeTransformer.h"
+#import "BUYDateTransformer.h"
+#import "NSArray+BUYAdditions.h"
+
+NSString * const BUYShippingRateDateTransformerName = @"BUYShippingRateDate";
+NSString * const BUYShippingRateDateFormat = @"yyyy-MM-dd'T'HH:mm:ss.SSSZ";
+
+@implementation BUYDeliveryRangeTransformer
+
++ (void)initialize
+{
+	static dispatch_once_t onceToken;
+	dispatch_once(&onceToken, ^{
+		[NSValueTransformer setValueTransformer:[BUYDateTransformer dateTransformerWithFormat:BUYShippingRateDateFormat] forName:BUYShippingRateDateTransformerName];
+	});
+}
+
+- (NSArray *)transformedValue:(NSArray *)value
+{
+	NSValueTransformer *dateTransformer = [NSValueTransformer valueTransformerForName:BUYShippingRateDateTransformerName];
+	return [value buy_map:^(NSDate *date) {
+		return [dateTransformer transformedValue:date];
+	}];
+}
+
+- (NSArray *)reverseTransformedValue:(NSArray *)value
+{
+	NSValueTransformer *dateTransformer = [NSValueTransformer valueTransformerForName:BUYShippingRateDateTransformerName];
+	return [value buy_map:^(NSString *dateString) {
+		return [dateTransformer reverseTransformedValue:dateString];
+	}];
+}
+
++ (BOOL)allowsReverseTransformation
+{
+	return YES;
+}
+
++ (Class)transformedValueClass
+{
+	return [NSString class];
+}
+
+@end

Mobile Buy SDK/Mobile Buy SDK/Value Transformers/BUYFlatCollectionTransformer.h

+//
+//  BUYFlatCollectionTransformer.h
+//  Mobile Buy SDK
+//
+//  Created by Shopify.
+//  Copyright (c) 2015 Shopify Inc. All rights reserved.
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in
+//  all copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+//  THE SOFTWARE.
+//
+
+#import <Foundation/Foundation.h>
+
+/**
+ * Transforms an array of objects into a string with given separator.
+ */
+@interface BUYFlatCollectionTransformer : NSValueTransformer
++ (instancetype)arrayTransformerWithElementTransformer:(NSValueTransformer *)elementTransformer separator:(NSString *)separator;
++ (instancetype)setTransformerWithElementTransformer:(NSValueTransformer *)elementTransformer separator:(NSString *)separator;
++ (instancetype)orderedSetTransformerWithElementTransformer:(NSValueTransformer *)elementTransformer separator:(NSString *)separator;
+
+/**
+ * Default to using the identity transformer and a space as separator.
+ */
++ (instancetype)arrayTransformer;
++ (instancetype)setTransformer;
+
++ (instancetype)arrayTransformerWithSeparator:(NSString *)separator;
++ (instancetype)setTransformerWithSeparator:(NSString *)separator;
+
+@end

Mobile Buy SDK/Mobile Buy SDK/Value Transformers/BUYFlatCollectionTransformer.m

+//
+//  BUYFlatCollectionTransformer.m
+//  Mobile Buy SDK
+//
+//  Created by Shopify.
+//  Copyright (c) 2015 Shopify Inc. All rights reserved.
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in
+//  all copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+//  THE SOFTWARE.
+//
+
+#import "BUYFlatCollectionTransformer.h"
+#import "BUYIdentityTransformer.h"
+
+#import "NSArray+BUYAdditions.h"
+
+@interface BUYFlatCollectionTransformer ()
+@property (nonatomic, weak) Class collectionClass;
+@property (nonatomic, strong) NSValueTransformer *elementTransformer;
+@property (nonatomic, strong) NSString *separator;
+@end
+
+@implementation BUYFlatCollectionTransformer
+
++ (instancetype)collectionTransformerWithClass:(Class)klass elementTransformer:(NSValueTransformer *)elementTransformer separator:(NSString *)separator
+{
+	BUYFlatCollectionTransformer *transformer = [[BUYFlatCollectionTransformer alloc] init];
+	transformer.collectionClass = klass;
+	transformer.separator = separator;
+	transformer.elementTransformer = elementTransformer;
+	return transformer;
+}
+
++ (instancetype)arrayTransformerWithElementTransformer:(NSValueTransformer *)elementTransformer separator:(NSString *)separator
+{
+	return [self collectionTransformerWithClass:[NSArray class] elementTransformer:elementTransformer separator:separator];
+}
+
++ (instancetype)arrayTransformer
+{
+	return [self arrayTransformerWithElementTransformer:[[BUYIdentityTransformer alloc] init] separator:@" "];
+}
+
++ (instancetype)arrayTransformerWithSeparator:(NSString *)separator
+{
+	return [self arrayTransformerWithElementTransformer:[[BUYIdentityTransformer alloc] init] separator:separator];
+}
+
++ (instancetype)setTransformerWithElementTransformer:(NSValueTransformer *)elementTransformer separator:(NSString *)separator
+{
+	return [self collectionTransformerWithClass:[NSSet class] elementTransformer:elementTransformer separator:separator];
+}
+
++ (instancetype)setTransformerWithSeparator:(NSString *)separator
+{
+	return [self setTransformerWithElementTransformer:[[BUYIdentityTransformer alloc] init] separator:separator];
+}
+
++ (instancetype)setTransformer
+{
+	return [self setTransformerWithSeparator:@" "];
+}
+
++ (instancetype)orderedSetTransformerWithElementTransformer:(NSValueTransformer *)elementTransformer separator:(NSString *)separator
+{
+	return [self collectionTransformerWithClass:[NSOrderedSet class] elementTransformer:elementTransformer separator:separator];
+}
+
++ (instancetype)orderedSetTransformerWithSeparator:(NSString *)separator
+{
+	return [self orderedSetTransformerWithElementTransformer:[[BUYIdentityTransformer alloc] init] separator:separator];
+}
+
++ (Class)transformedValueClass
+{
+	return [NSString class];
+}
+
++ (BOOL)allowsReverseTransformation
+{
+	return YES;
+}
+
+- (NSString *)transformedValue:(id)value
+{
+	return [[[value buy_array] buy_map:^(id element) {
+		return [_elementTransformer transformedValue:element];
+	}] componentsJoinedByString:self.separator];
+}
+
+- (id)reverseTransformedValue:(NSString *)value
+{
+	NSArray *array = [[value componentsSeparatedByString:self.separator] buy_map:^(NSString *string) {
+		return [_elementTransformer reverseTransformedValue:string];
+	}];
+	return [_collectionClass buy_convertArray:array];
+}
+
+@end

Mobile Buy SDK/Mobile Buy SDK/Value Transformers/BUYIdentityTransformer.h

+//
+//  BUYIdentityTransformer.h
+//  Mobile Buy SDK
+//
+//  Created by Shopify.
+//  Copyright (c) 2015 Shopify Inc. All rights reserved.
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in
+//  all copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+//  THE SOFTWARE.
+//
+
+#import <Foundation/Foundation.h>
+
+extern NSString * const BUYIdentityTransformerName; //  = @"BUYIdentity";
+
+/**
+ * Transforms a value into itself.
+ */
+@interface BUYIdentityTransformer : NSValueTransformer
+
+@end

Mobile Buy SDK/Mobile Buy SDK/Value Transformers/BUYIdentityTransformer.m

+//
+//  BUYIdentityTransformer.m
+//  Mobile Buy SDK
+//
+//  Created by Shopify.
+//  Copyright (c) 2015 Shopify Inc. All rights reserved.
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in
+//  all copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+//  THE SOFTWARE.
+//
+
+#import "BUYIdentityTransformer.h"
+
+NSString * const BUYIdentityTransformerName = @"BUYIdentity";
+
+@implementation BUYIdentityTransformer
+
+- (id)transformedValue:(id)value
+{
+	return value;
+}
+
+- (id)reverseTransformedValue:(id)value
+{
+	return value;
+}
+
++ (BOOL)allowsReverseTransformation
+{
+	return YES;
+}
+
++ (Class)transformedValueClass
+{
+	return [NSObject class];
+}
+
+@end

Mobile Buy SDK/Mobile Buy SDK/Value Transformers/BUYURLTransformer.h

+//
+//  BUYURLTransformer.h
+//  Mobile Buy SDK
+//
+//  Created by Shopify.
+//  Copyright (c) 2015 Shopify Inc. All rights reserved.
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in
+//  all copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+//  THE SOFTWARE.
+//
+
+#import <Foundation/Foundation.h>
+
+extern NSString * const BUYURLTransformerName; // = @"BUYURL";
+
+/**
+ * Transforms a URL object into a string and back.
+ */
+@interface BUYURLTransformer : NSValueTransformer
+@end

Mobile Buy SDK/Mobile Buy SDK/Value Transformers/BUYURLTransformer.m

+//
+//  BUYURLTransformer.m
+//  Mobile Buy SDK
+//
+//  Created by Shopify.
+//  Copyright (c) 2015 Shopify Inc. All rights reserved.
+//
+//  Permission is hereby granted, free of charge, to any person obtaining a copy
+//  of this software and associated documentation files (the "Software"), to deal
+//  in the Software without restriction, including without limitation the rights
+//  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+//  copies of the Software, and to permit persons to whom the Software is
+//  furnished to do so, subject to the following conditions:
+//
+//  The above copyright notice and this permission notice shall be included in
+//  all copies or substantial portions of the Software.
+//
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+//  THE SOFTWARE.
+//
+
+#import "BUYURLTransformer.h"
+
+NSString * const BUYURLTransformerName = @"BUYURL";
+
+@implementation BUYURLTransformer
+
++ (Class)transformedValueClass
+{
+	return [NSString class];
+}
+
++ (BOOL)allowsReverseTransformation
+{
+	return YES;
+}
+
+- (id)transformedValue:(NSURL *)value
+{
+	return [value absoluteString];
+}
+
+- (id)reverseTransformedValue:(NSString *)value
+{
+	return [NSURL URLWithString:value];
+}
+
+@end