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我创建用下面的代码的对象：的NSManagedObjectContext保存出现失去对象
+(Checkin *) newCheckinWithId:(NSString*) checkinID forVenueId:(NSString *)venueId
{
NSManagedObjectContext * context = [[AppDelegate sharedInstance] managedObjectContext];
Checkin *ret = (Checkin *)[NSEntityDescription insertNewObjectForEntityForName:@"Checkin" inManagedObjectContext:context];
ret.checkinID = checkinID;
ret.forVenueID = venueId;
ret.date = [NSDate date];
NSError * error;
if(![context save:&error]) {
NSLog(@"Error saving!!!!!: %@", error.userInfo);
}
return ret;
}
并没有错误，但之后保存我再也瑟该对象的任何记录。
运行在此功能的调试器我看到它有1个对象unprocessedInserts后保存在上下文中的所有内部设置0的对象（我不知道如果多数民众赞成预期与否。
这里是代码中，我用它来创建我的商店+管理对象上下文（我用的一切1个上下文）它基本上都来自一个堆栈溢出后，我发现
- (NSManagedObjectModel *)managedObjectModel
{
if (_managedObjectModel != nil)
{
return _managedObjectModel;
}
//NSURL *modelURL = [[NSBundle mainBundle] URLForResource:@"Model" withExtension:@"momd"];
//__managedObjectModel = [[NSManagedObjectModel alloc] initWithContentsOfURL:modelURL];
//NSArray *testArray = [[NSBundle mainBundle] URLsForResourcesWithExtension:@"momd"subdirectory:nil];
NSString *path = [[NSBundle mainBundle] pathForResource:@"Model" ofType:@"momd"];
if(!path) path = [[NSBundle mainBundle] pathForResource:@"Model" ofType:@"mom"];
NSURL *modelURL = [NSURL fileURLWithPath:path];
_managedObjectModel = [[NSManagedObjectModel alloc] initWithContentsOfURL:modelURL];
//__managedObjectModel = [NSManagedObjectModel mergedModelFromBundles:nil];
return _managedObjectModel;
}
- (NSPersistentStoreCoordinator *)persistentStoreCoordinator
{
if((_persistentStoreCoordinator != nil)) {
return _persistentStoreCoordinator;
}
_persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] initWithManagedObjectModel: [self managedObjectModel]];
NSPersistentStoreCoordinator *psc = _persistentStoreCoordinator;
// Set up iCloud in another thread:
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
// ** Note: if you adapt this code for your own use, you MUST change this variable:
NSString *iCloudEnabledAppID = @"[MY APP ID]";
// ** Note: if you adapt this code for your own use, you should change this variable:
NSString *dataFileName = @"foursquareaugmentation.sqlite";
// ** Note: For basic usage you shouldn't need to change anything else
NSString *iCloudDataDirectoryName = @"Data.nosync";
NSString *iCloudLogsDirectoryName = @"Logs";
NSFileManager *fileManager = [NSFileManager defaultManager];
NSURL *localStore = [[self applicationDocumentsDirectory] URLByAppendingPathComponent:dataFileName];
NSURL *iCloud = [fileManager URLForUbiquityContainerIdentifier:nil];
if (iCloud) {
NSLog(@"iCloud is working");
NSURL *iCloudLogsPath = [NSURL fileURLWithPath:[[iCloud path] stringByAppendingPathComponent:iCloudLogsDirectoryName]];
NSLog(@"iCloudEnabledAppID = %@",iCloudEnabledAppID);
NSLog(@"dataFileName = %@", dataFileName);
NSLog(@"iCloudDataDirectoryName = %@", iCloudDataDirectoryName);
NSLog(@"iCloudLogsDirectoryName = %@", iCloudLogsDirectoryName);
NSLog(@"iCloud = %@", iCloud);
NSLog(@"iCloudLogsPath = %@", iCloudLogsPath);
if([fileManager fileExistsAtPath:[[iCloud path] stringByAppendingPathComponent:iCloudDataDirectoryName]] == NO) {
NSError *fileSystemError;
[fileManager createDirectoryAtPath:[[iCloud path] stringByAppendingPathComponent:iCloudDataDirectoryName]
withIntermediateDirectories:YES
attributes:nil
error:&fileSystemError];
if(fileSystemError != nil) {
NSLog(@"Error creating database directory %@", fileSystemError);
}
}
NSString *iCloudData = [[[iCloud path]
stringByAppendingPathComponent:iCloudDataDirectoryName]
stringByAppendingPathComponent:dataFileName];
NSLog(@"iCloudData = %@", iCloudData);
NSMutableDictionary *options = [NSMutableDictionary dictionary];
[options setObject:[NSNumber numberWithBool:YES] forKey:NSMigratePersistentStoresAutomaticallyOption];
[options setObject:[NSNumber numberWithBool:YES] forKey:NSInferMappingModelAutomaticallyOption];
[options setObject:iCloudEnabledAppID forKey:NSPersistentStoreUbiquitousContentNameKey];
[options setObject:iCloudLogsPath forKey:NSPersistentStoreUbiquitousContentURLKey];
[psc lock];
NSError *error;
[psc addPersistentStoreWithType:NSSQLiteStoreType
configuration:nil
URL:[NSURL fileURLWithPath:iCloudData]
options:options
error:&error];
if(error)
{
NSLog(@"Error adding persistent store %@, %@", error, [error userInfo]);
// comment in this line while debugging if get "Can't find model for source store" error in addPersistentStoreWithType.
// it means the sqlite database doesn't match the new model and needs to be created from scratch.
// this happens if you change the xcdatamodel instead of creating a new one under Xcode->Editor->Add Model Version...
// CoreData can only automatically migrate if there is a new model version (it can't migrate if the model simply changes, because it can't see the difference between the two models).
// be sure to back up the database if needed, because all data will be lost.
//[fileManager removeItemAtPath:iCloudData error:&error];
/*// this is another way to verify the hashes for the database's model to make sure they match one of the entries in the momd directory's VersionInfo.plist
NSDictionary *sourceMetadata = [NSPersistentStoreCoordinator metadataForPersistentStoreOfType:NSSQLiteStoreType URL:[NSURL fileURLWithPath:iCloudData] error:&error];
if(!sourceMetadata)
NSLog(@"sourceMetadata is nil");
else
NSLog(@"sourceMetadata is %@", sourceMetadata);*/
}
[psc unlock];
}
else {
NSLog(@"iCloud is NOT working - using a local store");
NSMutableDictionary *options = [NSMutableDictionary dictionary];
[options setObject:[NSNumber numberWithBool:YES] forKey:NSMigratePersistentStoresAutomaticallyOption];
[options setObject:[NSNumber numberWithBool:YES] forKey:NSInferMappingModelAutomaticallyOption];
[psc lock];
NSError *error;
[psc addPersistentStoreWithType:NSSQLiteStoreType
configuration:nil
URL:localStore
options:options
error:nil];
if(error)
NSLog(@"Error adding persistent store %@, %@", error, [error userInfo]);
[psc unlock];
}
dispatch_async(dispatch_get_main_queue(), ^{
[[NSNotificationCenter defaultCenter] postNotificationName:@"SomethingChanged" object:self userInfo:nil];
});
});
return _persistentStoreCoordinator;
}
/*
Returns the managed object context for the application.
If the context doesn't already exist, it is created and bound to the persistent store coordinator for the application.
*/
- (NSManagedObjectContext *) managedObjectContext
{
if (_managedObjectContext != nil) {
return _managedObjectContext;
}
NSPersistentStoreCoordinator *coordinator = [self persistentStoreCoordinator];
if (coordinator != nil) {
_managedObjectContext = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSMainQueueConcurrencyType];
[_managedObjectContext setPersistentStoreCoordinator: coordinator];
}
return _managedObjectContext;
}
我一直工作在这个安静了一会儿，我出去的事情要尝试，所以任何帮助或调试步骤将不胜感激。（也不工作在icloud或本地）
也许我在提取错误，这就是为什么我没有得到对象。这里是我的提取：
+(NSArray *) checkinsForVenue:(NSString *) venueID
{
NSManagedObjectContext * context = [[AppDelegate sharedInstance] managedObjectContext];
NSEntityDescription *entity = [NSEntityDescription entityForName:@"Checkin" inManagedObjectContext:context];
NSFetchRequest *request = [[NSFetchRequest alloc] init];
request.entity = entity;
//NSPredicate *predicate = [NSPredicate predicateWithFormat:@"(forVenueID = %@)", venueID];
//request.predicate = predicate;
NSError *error;
NSArray * ret = [context executeFetchRequest:request error:&error];
if(ret == nil) {
NSLog(@"%@", error.description);
}
return ret;
}
编辑：我问的是错误的问题。储蓄是工作获取不是。仍然无法弄清楚我的抓取有什么问题。
也是我能想到的一切似乎正常Checkin * ret =（Checkin *）[NSEntityDescription insertNewObjectForEntityForName：@“Checkin”inManagedObjectContext：context];返回一个好的对象;上下文不是零，等不知道还有什么其他检查 – mike 2013-03-08 02:39:50