managedObjectContext问题

Question

我有一个应用程序，其是一个的UITabBarController，我已经定义了两个子视图

两个翼片具有在Identity检查他们的类属性设置为UINavigationController的。

现在我设法得到这个很远，我的代码后非常长的审判。

- (void)viewDidLoad { 
[super viewDidLoad]; 

myAppDelegate *appDelegate = (myAppDelegate *)[[UIApplication sharedApplication] delegate]; 
self.managedObjectContext = appDelegate.managedObjectContext; 

{ 



    NSError *error = nil; 
    NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init]; 
    [fetchRequest setEntity:[NSEntityDescription entityForName:@"User" inManagedObjectContext:self.managedObjectContext]]; 
    NSArray *fetchedItems = [self.managedObjectContext executeFetchRequest:fetchRequest error:&error]; 

    NSEntityDescription *entityDesc = 
    [NSEntityDescription entityForName:@"User" inManagedObjectContext:self.managedObjectContext]; 

    // replace the old data with new. this DOESNT WORK 
    if (fetchedItems.count > 0) 
    { 
    Usr *newUsr; 
    for (newUsr in fetchedItems) 
    { 
    if ([newUsr.name isEqualToString:@"Line One"]) 
    { 

    newUsr.uName = @"Line One (new)"; 

    } 
    } 
    } 

    //add a new default data. THIS ADDS DATA TO MY TABLEVIEW BUT IT DOESNT SAVE THEM TO THE SQLITE 
    User *addedDefaultdata = nil; 
    addedDefaultdata = [[User alloc] initWithEntity:entityDesc insertIntoManagedObjectContext:self.managedObjectContext]; 
    addedDefaultdata.name = @"Added new 1"; 
    [addedDefaultdata release]; 
} 


NSError *error = nil; 
if (![User.managedObjectContext save:&error]) { 

    NSLog(@"Unresolved error %@, %@", error, [error userInfo]); 
    abort(); 
} 

} 

和我的appdelegate看起来是这样的：

- (void)applicationDidFinishLaunching:(UIApplication *)application {  

[application setStatusBarStyle:UIStatusBarStyleBlackOpaque]; 


[window addSubview:navigationController.view]; 
[window makeKeyAndVisible]; 

} 

，现在我不能一刀 “用户” 在所有！尽管我没有得到任何错误或警告！

任何建议将不胜感激！

谢谢

Answer 1

看来你可能会问如何更新到CoreData？

如果是这样，你需要使用上NSManagedObjectContext的​​方法，像这样：

NSError *error; 
[managedObjectContent save:&error]; 
if (error) { 
    ... 
}