核心数据对象不会存储

我已经开始将核心数据集成到当前项目中，这是我第一次使用它。核心数据对象不会存储

我已经设法将新对象写入我的NSManagedObjectContext并将其读出。我的问题是，在关闭应用程序后，所有对象都会丢失。这里是添加新对象的功能之一：

-(void)addExpenseWithValue:(NSNumber *)value name:(NSString *)name type:(BOOL)type andDate:(NSDate *)date{ 

//get the right managed object context 
NSManagedObjectContext *context = self.managedObjectContext;  

//creat a new expense in context 
NSManagedObject *newExpense = [NSEntityDescription insertNewObjectForEntityForName:@"Expense" inManagedObjectContext:context]; 

//Get Number representation of month and year 
NSNumber *monthNumber = [self getMonthNumber:date]; 
NSNumber *dayNumber = [self getDayNumber:date]; 

//set values of the expense 
[newExpense setValue:[NSDate date] forKey:@"date"]; 
[newExpense setValue:value forKey:@"value"]; 
[newExpense setValue:name forKey:@"name"]; 
[newExpense setValue:[NSNumber numberWithBool:type ] forKey:@"expenseType"]; 
[newExpense setValue:monthNumber forKey:@"month"]; 
[newExpense setValue:dayNumber forKey:@"day"]; 
[self storeData]; 
} 


-(void)storeData{ 
NSError *error = nil; 
[managedObjectContext save:&error]; 

}

对象实际上是存储的，我可以在之后读出它们。据我所知它与persistentStore和persistentStoreCoordinator有关。我appDelegate有以下方法来实现：

- (NSPersistentStoreCoordinator *)persistentStoreCoordinator { 
if (persistentStoreCoordinator != nil) { 
    return persistentStoreCoordinator; 
} 
NSURL *storeUrl = [NSURL fileURLWithPath: [[self applicationDocumentsDirectory] 
              stringByAppendingPathComponent: @"<Project Name>.sqlite"]]; 
NSError *error = nil; 
persistentStoreCoordinator = [[NSPersistentStoreCoordinator alloc] 
           initWithManagedObjectModel:[self managedObjectModel]]; 
if(![persistentStoreCoordinator addPersistentStoreWithType:NSSQLiteStoreType 
              configuration:nil URL:storeUrl options:nil error:&error]) { 
    /*Error for store creation should be handled in here*/ 
} 

return persistentStoreCoordinator; 
} 

- (NSManagedObjectContext *) managedObjectContext { 
if (managedObjectContext != nil) { 
    return managedObjectContext; 
} 

NSPersistentStoreCoordinator *coordinator = [self persistentStoreCoordinator]; 
if (coordinator != nil) { 
    managedObjectContext = [[NSManagedObjectContext alloc] init]; 
    [managedObjectContext setPersistentStoreCoordinator: coordinator]; 
} 

return managedObjectContext; 
} 

- (NSManagedObjectModel *)managedObjectModel { 
if (managedObjectModel != nil) { 
    return managedObjectModel; 
} 
managedObjectModel = [NSManagedObjectModel mergedModelFromBundles:nil] ; 

return managedObjectModel; 
} 



- (NSString *)applicationDocumentsDirectory { 
return [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) lastObject]; 
}

UPDATE：

我添加了一个小testfunction，尝试它被称为第一的viewController：

-(void)test{ 

NSArray* stores = [[managedObjectContext persistentStoreCoordinator]persistentStores]; 
if ([stores objectAtIndex:0]==nil) { 
    NSLog(@"no stores found"); 
} 
else 
    NSLog(@"%d", [stores count]); 

}

managedObjectContext是应用NSanagedObjectContext如在appdelegate中发起的那样。它的存在，则数组被分配，但计数停留在0

2012-03-06 20:09:37.772 DailyBudget[1533:fb03] *** Terminating app due to uncaught 
exception 'NSRangeException', reason: '*** -[__NSArrayI objectAtIndex:]: index 0 beyond  
bounds for empty array' 
*** First throw call stack: 
(0x135f052 0x174fd0a 0x134b674 0x3c6a 0x3894 0x46cfbf 0x46d21b 0x4838b1 0x46cfbf 
0x46d21b 0x46e0f1 0x3dcfec 0x3e2572 0x3dc72b 0x3cbbc2 0x3cbce2 0x3cbea8 0x3d2d9a 0x25b3 
0x3a39d6 0x3a48a6 0x3b3743 0x3b41f8 0x3a7aa9 0x1f57fa9 0x13331c5 0x1298022 0x129690a 
0x1295db4 0x1295ccb 0x3a42a7 0x3a5a9b 0x2488 0x23e5 0x1) 
terminate called throwing an exception(gdb)

的错误，我有以下对象的时刻：

objects that exist

我失去了什么？

来源

2012-03-05 Sebastian Flückiger

错误是否为无？ [managedObjectContext save：＆error]是否为TRUE？ – NeverBe 2012-03-05 22:14:31

如果您使用'NSArrayController'来显示数据，请确保它们具有'setAutomaticallyPreparesContent：YES'（类似于IB中的“准备内容”）。 – spudwaffle 2012-03-06 06:51:29

你可以检查持久存储的创建是否正常？ - [NSPersistentStoreCoordinator persistentStores]返回什么？ – Aderstedt 2012-03-06 06:58:54

... 24小时后。我不知何故能够自己解决=）我认为这个问题存在于storeURL中。我的新代码从这个帖子在这里受到启发：

Adding CoreData to Existing Project (theappcodeblog.com)

感谢您的家伙检查出来，反正=）

新代码（工作）：

NSURL *storeURL = [[self applicationDocumentsDirectory] URLByAppendingPathComponent:@"CoreDataTabBarTutorial.sqlite"];

与功能

- (NSURL *)applicationDocumentsDirectory { 
    return [[[NSFileManager defaultManager] URLsForDirectory:NSDocumentDirectory inDomains:NSUserDomainMask] lastObject]; 
}

来源

2012-03-07 12:58:22

核心数据对象不会存储

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