这是我使用 RestKit 的第一个项目，我试图让我的简单 iOS 应用程序与使用 Tastypie 包的 Django 应用程序提供的一组 API 同步。我的 iOS 应用程序基于 Core Data Default Xcode 应用程序。
我正在尝试从一个简单的模型中检索对象：
Car (name (string), public (boolean), id (integer), created (datetime))
我的 API 看起来像这样的集合：
http://www.example.com/api/v1/car/?format=json
{"meta": {"limit": 20, "next": null, "offset": 0, "previous": null, "total_count": 1}, "objects": [{"created": "2012-07-04T13:47:37+00:00", "id": "1", "name": "BMW", "public": true, "resource_uri": "\/api\/v1\/car\/1\/",}]}
对于 1 个对象：
http://www.example.com/api/v1/car/1/?format=json
{"created": "2012-07-04T13:47:37+00:00", "id": "1", "name": "BMW", "public": true, "resource_uri": "\/api\/v1\/car\/1\/",}
鉴于这种情况，在我的 iOS 应用程序中，我在我的应用程序委托中配置了我的商店
-(void)configureObjectStore {
// Initialize the RestKit Object Manager
RKObjectManager *objectManager = [RKObjectManager objectManagerWithBaseURL:[[NSURL alloc] initWithString:@"http://www.example.com/api/v1"]];
objectManager.client.requestQueue.showsNetworkActivityIndicatorWhenBusy = YES;
// Initialize object store
objectManager.objectStore = [RKManagedObjectStore objectStoreWithStoreFilename:@"database.sqlite"];
[self coreDataMapping];
}
并通过 Application Delegate 设置我的映射（不确定这应该在这里......）
- (void)coreDataMapping {
// Now for the object mappings
NSEntityDescription *entity = [NSEntityDescription entityForName:@"Car" inManagedObjectContext:self.managedObjectContext];
RKManagedObjectMapping* carMapping = [RKManagedObjectMapping mappingForEntity:entity inManagedObjectStore:[RKObjectManager sharedManager].objectStore];
[carMapping mapKeyPath:@"id" toAttribute:@"carId"];
[carMapping mapAttributes:@"name", nil];
[carMapping mapKeyPath:@"public" toAttribute:@"public"];
[carMapping mapKeyPath:@"created" toAttribute:@"created"];
carMapping.primaryKeyAttribute = @"carId";
[[RKObjectManager sharedManager].mappingProvider addObjectMapping:carMapping];
}
然后在我的主控制器中，我想在表格视图中加载我的所有对象（所有汽车）
- (void)loadData {
// Load the object model via RestKit
RKObjectManager* objectManager = [RKObjectManager sharedManager];
[objectManager loadObjectsAtResourcePath:@"/car/1/?format=json" usingBlock:^(RKObjectLoader *loader) {
loader.objectMapping = [objectManager.mappingProvider objectMappingForClass:[Car class]];
loader.delegate = self;
}];
}
当我启动我的应用程序并尝试加载对象列表时，它会从委托中触发 didFailWithError 方法，并且我有以下堆栈：
I restkit.core_data:RKInMemoryManagedObjectCache.m:34 Creating thread-local entity cache for managed object context: <NSManagedObjectContext: 0x887f1b0>
I restkit.core_data:RKInMemoryManagedObjectCache.m:50 Caching instances of Entity 'Car' by primary key attribute 'carId'
E restkit.core_data:RKManagedObjectStore.m:262 Core Data Save Error
NSLocalizedDescription: (null)
NSValidationErrorKey: (null)
NSValidationErrorPredicate: (null)
NSValidationErrorObject: (null)
E restkit.core_data:RKManagedObjectLoader.m:167 Failed to save managed object context after mapping completed: The operation couldn’t be completed. (Cocoa error 134020.)
Hit error: Error Domain=NSCocoaErrorDomain Code=134020 "The operation couldn’t be completed. (Cocoa error 134020.)" UserInfo=0x89612c0 {NSAffectedObjectsErrorKey=<Car: 0x6c85670> (entity: Car; id: 0x6c65790 <x-coredata:///Car/t318CE65F-E4FE-44E1-813B-GEZG54> ; data: {
created = "2012-07-04 13:47:37 +0000";
favorites = (); (Note this relation is not mapped in the API but it is not required)
carId = 1;
modified = nil;
name = BMW;
public = 1;
}), NSUnderlyingException=Store <NSSQLCore: 0x88848c0> (URL: file://localhost/Users/me/Library/Application%20Support/Documents/database.sqlite) cannot hold instances of entity (<NSEntityDescription: 0x886f650>) name Car, managedObjectClassName Car, renamingIdentifier Car, isAbstract 0, superentity name (null), properties {
created = "(<NSAttributeDescription: 0x886dce0>), name created, isOptional 1, isTransient 0, entity Car, renamingIdentifier created, validation predicates (\n), warnings (\n), versionHashModifier (null)\n userInfo {\n}, attributeType 900 , attributeValueClassName NSDate, defaultValue (null)";
favorites = "(<NSRelationshipDescription: 0x886e900>), name favorites, isOptional 1, isTransient 0, entity Car, renamingIdentifier favorites, validation predicates (\n), warnings (\n), versionHashModifier (null)\n userInfo {\n}, destination entity Favorite, inverseRelationship list, minCount 0, maxCount 0, isOrdered 0, deleteRule 1";
carId = "(<NSAttributeDescription: 0x886dd80>), name carId, isOptional 1, isTransient 0, entity Car, renamingIdentifier carId, validation predicates (\n), warnings (\n), versionHashModifier (null)\n userInfo {\n}, attributeType 100 , attributeValueClassName NSNumber, defaultValue 0";
name = "(<NSAttributeDescription: 0x886de20>), name name, isOptional 1, isTransient 0, entity Car, renamingIdentifier name, validation predicates (\n), warnings (\n), versionHashModifier (null)\n userInfo {\n}, attributeType 700 , attributeValueClassName NSString, defaultValue (null)";
public = "(<NSAttributeDescription: 0x886de70>), name public, isOptional 1, isTransient 0, entity Car, renamingIdentifier public, validation predicates (\n), warnings (\n), versionHashModifier (null)\n userInfo {\n}, attributeType 800 , attributeValueClassName NSNumber, defaultValue (null)";
}, subentities (null), userInfo {
}, versionHashModifier (null)}
我已经尝试了很多东西，但我觉得我在这里转了一圈。任何建议都将受到热烈欢迎。
感谢您的时间和支持，问候，
PS：我们应该能够排除与 RestKit 无关的错误，因为在集成之前应用程序运行顺利。