iphone - 从 tableView 和 coredata 中删除一行

Question

我正在从 coredata 中检索数据并将其显示在 tableview 中。如果用户点击一行，它将导航到另一个 View (比如 View 2)。

现在，我想从 tableview 和 coredata 中删除一行。我使用了一个代码，可以删除该行。但是，当我去查看 2 并返回时，记录又回到了那里。 (它已从 coredata 中删除，但该行及其数据仍然存在，直到我重新加载 View )。

这是我使用的代码。

- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath
{
    if (editingStyle == UITableViewCellEditingStyleDelete) 
    {
        NSManagedObjectContext *context = [self.fetchedResultsController managedObjectContext];
        [context deleteObject:[self.fetchedResultsController objectAtIndexPath:indexPath]];
        NSError *error;
        if (![context save:&error]) 
        {
            UIAlertView *alertView = [[UIAlertView alloc]initWithTitle:@"App" message:@"Sorry the Item Cannot be deleted" delegate:nil cancelButtonTitle:@"Ok" otherButtonTitles:nil];
            [alertView show];
            [alertView release];
        }
    }
}

Answer 1

删除后，您是否尝试过使用 reloadData，

if (editingStyle == UITableViewCellEditingStyleDelete) 
  {
   NSManagedObjectContext *context = [self.fetchedResultsController managedObjectContext];
   [context deleteObject:[self.fetchedResultsController objectAtIndexPath:indexPath]];
   NSError *error;
   if (![context save:&error]) 
     {
        UIAlertView *alertView = [[UIAlertView alloc]initWithTitle:@"Xpense Tracker" message:@"Sorry the Item Cannot be deleted" delegate:nil cancelButtonTitle:@"Ok" otherButtonTitles:nil];
        [alertView show];
        alertView release];
     }
   [YOURTABLEVIEW reloadData];
  }

已编辑:它现在工作正常。试试这个方法

Step 1:

@interface ViewController : UIViewController <UITableViewDataSource,UITableViewDelegate,NSFetchedResultsControllerDelegate>

Step 2:

update your 
-(NSFetchedResultsController *)fetchedResultsController{
self.fetchedResultsController.delegate = self; // with this
}

step 3:

- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section
{
    id <NSFetchedResultsSectionInfo> sectionInfo = [[self.fetchedResultsController sections] objectAtIndex:section];
    return [sectionInfo numberOfObjects];
}

- (BOOL)tableView:(UITableView *)tableView canEditRowAtIndexPath:(NSIndexPath *)indexPath
{
    return YES;
}

- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath
{
    if (editingStyle == UITableViewCellEditingStyleDelete)
    {
        NSManagedObjectContext * context = [self.fetchedResultsController managedObjectContext];
        [context deleteObject:[self.fetchedResultsController objectAtIndexPath:indexPath]];
        NSError * error;
        if (![context save:&error])
        {
            NSLog(@"Deletion Error");
        }
    }

}

Step 4:

include NSFetchedResultsControllerDelegate method 
- (void)controllerDidChangeContent:(NSFetchedResultsController *)controller {
    [YOURTABLEVIEW reloadData];
}