我一直在浏览 RestKit 的文档，但我无法弄清楚有关的一些细节RKMappingResult.
我有创建一个的代码NSManagedObject，称为newUser，并插入到mainQueueManagedObjectContextRestKit RKManagedObjectStore 的。然后我使用我的对象管理器postObject:path:parameters:success:failure:将用户发布到服务器的方法。这看起来效果很好。
我需要更新一些字段newUser当 post 请求完成时，托管对象不会从 post 请求的结果映射。这mappingResult传递到块中的参数似乎具有与服务器响应中设置的所有字段正确映射的托管对象。
显然，对象中的mappingResult与我发布的对象不是同一对象，因为它们不在同一线程中。如果我保存newUser在我发帖之前，他们会objectID当请求完成并返回映射结果时是否相同？
我想象着newUser映射结果中的对象引用存储在 CoreData 中的同一对象，是否正确？我问的原因是，事实似乎并非如此。如果我发出一个帖子请求并保存两个newUser对象和返回的对象mappingResult，我最终在核心数据中得到了两个不同的对象，一个用于newUser一个用于映射结果。我通过更改映射结果对象和newUser反对并发现它们都是独立改变的。此外，下次获取时会获取两个用户对象。我该如何防止这种情况？
然而，如果这是正确的，如果请求尚未完成而崩溃，会发生什么？我不会有一个存根对象挂在 CoreData 中吗？
如果请求失败，如何删除我创建的存根对象？我可以在故障块中执行类似以下操作吗？
dispatch_async(dispatch_get_main_queue(), ^{
[newUser.managedObjectContext deleteObject:newRegisteredUser];
});
Where newUser，是我在 mainQueue 上创建的托管对象。
最后，如果我通过映射结果在后台线程中返回托管对象，我无法将 returnedUser 设置为 UI 用来获取信息的用户，因为它位于主线程上，那么我如何通知UI 来更改其用户？我是否应该发布一条通知，告诉 UI 从 Core Data 重新获取活动用户？
关于重复对象的更新
我做了一些进一步的测试，当帖子返回时我肯定会得到一个重复的对象。
我首先创建一个newUser并为其设置属性：
HNGRRegisteredUser *newUser = [NSEntityDescription insertNewObjectForEntityForName:@"RegisteredUser" inManagedObjectContext:context];
newUser.firstName = @"John"
newUser.lastName = @"Smith"
newUser.gender = @"Male"
newUser.email = @"[email protected] /cdn-cgi/l/email-protection"
newUser.hungrosityModel = //fill in all of the attributes for a hungrosityModel, except uniqueID
此时，newUser.uniqueID == nil。然后我保存 newUser （我假设我必须这样做，以便 RestKit 可以使用永久 objectID）来创建存根对象。
NSError *saveError;
[newRegisteredUser.managedObjectContext saveToPersistentStore:&saveError];
if (saveError) NSLog(@"Save Error: %@", saveError);
NSLog(@"newUser objectID: %@", [newRegisteredUser.objectID URIRepresentation]);
然后我发布newUser object.
[[RKObjectManager sharedManager] postObject:newRegisteredUser path:@"users/" parameters:nil success:^(RKObjectRequestOperation *operation, RKMappingResult *mappingResult) {
NSError *saveError;
HNGRRegisteredUser *returnedUser = [mappingResult firstObject];
NSLog(@"mappingResult objectID: %@", [returnedUser.objectID URIRepresentation]);
[returnedUser.managedObjectContext saveToPersistentStore:&saveError];
if (saveError) NSLog(@"Error saving user upon registration: %@", saveError);
} failure:^(RKObjectRequestOperation *operation, NSError *error) {
[newUser.managedObjectContext deleteObject:newUser];
}];
objectID 的打印输出如下。
newUser objectID: x-coredata://B74AB613-1060-4D98-ABFC-3B4D89AB12C3/RegisteredUser/p2
mappingResult objectID: x-coredata://B74AB613-1060-4D98-ABFC-3B4D89AB12C3/RegisteredUser/p3
发送到服务器的 JSON 是：
{
"gender":"Male",
"lastName":"Smith",
"firstName":"John",
"email":"[email protected] /cdn-cgi/l/email-protection",
"hungrosityModel": {
"totalNumberOfUpdates":0,
"peakHungrosity":0.8,
"hungrosityFractionAtLastUpdate":0,
"rateOfHungrosification":5e-05,
"troughHungrosity":0.1,
"peakUpdates":0
}
}
从服务器返回的 JSON 为：
{"results": [
{"receivedFriendRequests": [],
"firstName": "John",
"middleName": null,
"hungrosityModel": {"uniqueID": 13},
"email": "[email protected] /cdn-cgi/l/email-protection",
"gender": "Male",
"lastName": "Smith",
"sentFriendRequests": [],
"uniqueID": 14,
"updatedAt": "2014-03-12T17:45:01.973Z",
"friends": [],
"profileImageUpdatedAt": null,
"createdAt": "2014-03-12T17:45:01.809Z"}
]}
对象的响应和请求描述符是：
[[RKObjectManager sharedManager].router.routeSet addRoute:[RKRoute routeWithClass:[HNGRRegisteredUser class] pathPattern:@"users/" method:RKRequestMethodPOST]];
RKResponseDescriptor *registrationResponseDescriptor = [RKResponseDescriptor responseDescriptorWithMapping:[HNGRRKMappingProvider registeredUserMapping] method:RKRequestMethodPOST pathPattern:@"users/" keyPath:@"results" statusCodes:RKStatusCodeIndexSetForClass(RKStatusCodeClassSuccessful)];
[[RKObjectManager sharedManager] addResponseDescriptor: registrationResponseDescriptor];
RKRequestDescriptor *registrationRequestDescriptor = [RKRequestDescriptor requestDescriptorWithMapping:[[HNGRRKMappingProvider registeredUserMapping] inverseMapping] objectClass:[HNGRRegisteredUser class] rootKeyPath:nil method:RKRequestMethodPOST];
[[RKObjectManager sharedManager] addRequestDescriptor:registrationRequestDescriptor];
用户的映射是：
RKEntityMapping *_mapping = nil;
_mapping = [RKEntityMapping mappingForEntityForName:@"RegisteredUser" inManagedObjectStore:[RKManagedObjectStore defaultStore]];
[_mapping addAttributeMappingsFromArray:@[@"uniqueID",
@"createdAt",
@"updatedAt",
@"firstName",
@"middleName",
@"lastName",
@"email",
@"gender",
@"profileImageUpdatedAt"]];
[_mapping addRelationshipMappingWithSourceKeyPath:@"hungrosityModel" mapping:[HNGRRKMappingProvider basicModelMapping]];
_mapping.identificationAttributes = @[@"uniqueID"];
这是相关的对象映射跟踪：
D restkit.object_mapping:RKMapperOperation.m:377 Executing mapping operation for representation: {
results = (
{
createdAt = "2014-03-12T18:22:35.688Z";
dateOfBirth = "2014-03-12T18:24:02Z";
firstName = John;
friends = (
);
gender = Male;
hungrosityModel = {
uniqueID = 14;
};
lastName = Smith;
middleName = "<null>";
profileImageUpdatedAt = "<null>";
receivedFriendRequests = (
);
sentFriendRequests = (
);
uniqueID = 14;
updatedAt = "2014-03-12T18:22:35.856Z";
}
);
}
and targetObject: <HNGRRegisteredUser: 0xaa8c180> (entity: RegisteredUser; id: 0xa894550 <x-coredata://44B8DF7A-BDC9-45F2-A137-BFAACF4AAF88/RegisteredUser/p2> ; data: {
createdAt = nil;
dateOfBirth = "2014-03-12 18:24:02 +0000";
email = "[email protected] /cdn-cgi/l/email-protection";
firstName = John;
friendRequests = "<relationship fault: 0xa899dd0 'friendRequests'>";
friends = "<relationship fault: 0xa891ea0 'friends'>";
gender = Male;
hungrosityModel = "0xa861980 <x-coredata://44B8DF7A-BDC9-45F2-A137-BFAACF4AAF88/BasicModel/p2>";
hungrosityUpdateEvents = "<relationship fault: 0xa829d90 'hungrosityUpdateEvents'>";
isLocalUser = 0;
lastName = Smith;
middleName = nil;
myInvitations = nil;
profileImageData = nil;
profileImageThumbnailData = nil;
profileImageUpdatedAt = nil;
receivedInvitations = nil;
registeredUserSettings = nil;
savedHungrosityComments = "<relationship fault: 0xa8bc450 'savedHungrosityComments'>";
uniqueID = nil;
updatedAt = nil;
user = nil;
userSettings = nil;
})
T restkit.object_mapping:RKMapperOperation.m:320 Examining keyPath 'results' for mappable content...
D restkit.object_mapping:RKMapperOperation.m:297 Found mappable collection at keyPath 'results': (
{
createdAt = "2014-03-12T18:22:35.688Z";
dateOfBirth = "2014-03-12T18:24:02Z";
firstName = John;
friends = (
);
gender = Male;
hungrosityModel = {
uniqueID = 14;
};
lastName = Smith;
middleName = "<null>";
profileImageUpdatedAt = "<null>";
receivedFriendRequests = (
);
sentFriendRequests = (
);
uniqueID = 14;
updatedAt = "2014-03-12T18:22:35.856Z";
}
)
D restkit.object_mapping:RKMappingOperation.m:952 Starting mapping operation...
T restkit.object_mapping:RKMappingOperation.m:953 Performing mapping operation: <RKMappingOperation 0xa8e4440> for 'HNGRRegisteredUser' object. Mapping values from object {
createdAt = "2014-03-12T18:22:35.688Z";
dateOfBirth = "2014-03-12T18:24:02Z";
firstName = John;
friends = (
);
gender = Male;
hungrosityModel = {
uniqueID = 14;
};
lastName = Smith;
middleName = "<null>";
profileImageUpdatedAt = "<null>";
receivedFriendRequests = (
);
sentFriendRequests = (
);
uniqueID = 14;
updatedAt = "2014-03-12T18:22:35.856Z";
} to object <HNGRRegisteredUser: 0xa8833b0> (entity: RegisteredUser; id: 0xa8777e0 <x-coredata:///RegisteredUser/t1FD3D8DE-75AD-4194-B157-EB6931B74BDB6> ; data: {
createdAt = nil;
dateOfBirth = nil;
email = nil;
firstName = nil;
friendRequests = (
);
friends = (
);
gender = nil;
hungrosityModel = nil;
hungrosityUpdateEvents = (
);
isLocalUser = 0;
lastName = nil;
middleName = nil;
myInvitations = nil;
profileImageData = nil;
profileImageThumbnailData = nil;
profileImageUpdatedAt = nil;
receivedInvitations = nil;
registeredUserSettings = nil;
savedHungrosityComments = (
);
uniqueID = 14;
updatedAt = nil;
user = nil;
userSettings = nil;
}) with object mapping (null)
如果还有更多有助于了解的信息，请告诉我。
