将对象从一个Core Data UITableView移动到另一个？

Question

我试图将一个对象从fetchedresultscontroller移动到另一个。代码如下所示：

UISegmentedControl *segmentedControl = self.navigationItem.titleView; 
NSManagedObject *managedObject = [fetchedResultsController objectAtIndexPath:indexPath]; 
NSDate *timeValue = [[managedObject valueForKey:@"timeStamp"] copy]; 

NSManagedObjectContext *context = [fetchedResultsController managedObjectContext]; 
[context deleteObject:[fetchedResultsController objectAtIndexPath:indexPath]]; 

NSError *error = nil; 
if (![context save:&error]) { 
    /* 
    Replace this implementation with code to handle the error appropriately. 

    abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development. If it is not possible to recover from the error, display an alert panel that instructs the user to quit the application by pressing the Home button. 
    */ 
    NSLog(@"Unresolved error %@, %@", error, [error userInfo]); 
    abort(); 
} 
[self.tableView reloadData]; 

fetchedResultsController = [fetchedResultsControllers objectAtIndex:(1-segmentedControl.selectedSegmentIndex)]; 
context = [fetchedResultsController managedObjectContext]; 
NSManagedObject *newManagedObject = [NSEntityDescription insertNewObjectForEntityForName:@"Picked" inManagedObjectContext:context]; 

[newManagedObject setValue:timeValue forKey:@"timeStamp"]; 

error = nil; 
if (![context save:&error]) { 
    /* 
    Replace this implementation with code to handle the error appropriately. 

    abort() causes the application to generate a crash log and terminate. You should not use this function in a shipping application, although it may be useful during development. If it is not possible to recover from the error, display an alert panel that instructs the user to quit the application by pressing the Home button. 
    */ 
    NSLog(@"Unresolved error %@, %@", error, [error userInfo]); 
    abort(); 
} 

fetchedResultsController = [fetchedResultsControllers objectAtIndex:(1-segmentedControl.selectedSegmentIndex)]; 

}

但它不工作。我得到的可怕：

Serious application error. Exception was caught during Core Data change processing: Invalid update: invalid number of rows in section 0. The number of rows contained in an existing section after the update (1) must be equal to the number of rows contained in that section before the update (2), plus or minus the number of rows inserted or deleted from that section (1 inserted, 0 deleted). with userInfo (null) 

我真的不知道如何得到它的工作。核心数据很难使用。

Answer 1

昨晚我自己遇到了这个问题。就我而言，我已经忘了来实现NSFetchedResultsControllerDelegate方法：

- (void)controller:(NSFetchedResultsController *)controller didChangeObject:(id)anObject atIndexPath:(NSIndexPath *)indexPath forChangeType:(NSFetchedResultsChangeType)type newIndexPath:(NSIndexPath *)newIndexPath; 
- (void)controller:(NSFetchedResultsController *)controller didChangeSection:(id <NSFetchedResultsSectionInfo>)sectionInfo atIndex:(NSUInteger)sectionIndex forChangeType:(NSFetchedResultsChangeType)type; 
- (void)controllerWillChangeContent:(NSFetchedResultsController *)controller; 
- (void)controllerDidChangeContent:(NSFetchedResultsController *)controller; 

的问题是这样的：你删除NSManagedObjectContext对象后，然后保存的背景下，UITableView是不同步的变化并且正在询问不存在的项目。

CoreDataBooks示例代码显示了如何在您的NSFetchedResultsController中添加/删除管理对象的同时实现这些功能。