Question

我有一个包含剖面的表视图。当我尝试从表视图中删除一行时，我收到以下错误.........

'无效更新：第5节中的行数无效。更新后的现有部分中包含的行数（4）必须等于更新前该部分中包含的行数（4）加上或减去从该部分插入或删除的行数（0插入，1删除）和加或减移入或移出该部分的行数（0移入，0移出）。'

经过一些在线研究后，我明白我必须从数组中删除对象。我使用标准managedObjectContext和fetchedResultsController的核心数据。我不明白这里的数组是什么。有人可以帮忙吗。

以下是节数和行数的代码....

- (NSInteger)numberOfSectionsInTableView:(UITableView *)tableView
{
    NSInteger count = [[self.fetchedResultsController sections] count];
    return count;
}


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

    NSInteger count = [sectionInfo numberOfObjects];
    return count;
}

以下是我用来删除行的代码....

- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath
{
    if (editingStyle == UITableViewCellEditingStyleDelete) {

        // Delete the managed object at the given index path.
        NSManagedObject *birthdayToDelete = [self.fetchedResultsController objectAtIndexPath:indexPath];
        [self.managedObjectContext deleteObject:birthdayToDelete];

        // Update the array and table view.
        [tableView deleteRowsAtIndexPaths:@[indexPath] withRowAnimation:YES];

        // Commit the change.
        NSError *error = nil;
        if (![self.managedObjectContext 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.
            NSLog(@"Unresolved error %@, %@", error, [error userInfo]);
            abort();
        }
    }

    [_birthdayTableView reloadData];
}

Answer 1

这通常是因为您的数组中的项目数量与numberOfRowsInSection:返回的数字不符，请确保您在编辑时正确调用beginUpdates和endUpdates。< / p>

Answer 2

如果您使用[tableView deleteRowsAtIndexPaths:@[indexPath] withRowAnimation:YES];委托方法，则无需致电NSFetchResultsController。实现以下内容：保存managedObjectContext帖子删除后将调用这些内容。（记得设置NSFetchedResultsController的委托。另外，不要打电话给[tableView reloadData];。它会让动画跳过并看起来很奇怪:-)这是使用NSFetchedResultsController的美妙之处，它确实如此对你来说很重要，并倾听managedObjectContext

的变化

- (void)controllerWillChangeContent:(NSFetchedResultsController *)controller
{
    [tableView beginUpdates];
}

- (void)controller:(NSFetchedResultsController *)controller didChangeSection:(id <NSFetchedResultsSectionInfo>)sectionInfo
           atIndex:(NSUInteger)sectionIndex forChangeType:(NSFetchedResultsChangeType)type
{
       switch(type) {
         case NSFetchedResultsChangeInsert:
             [tableView insertSections:[NSIndexSet indexSetWithIndex:sectionIndex]
                      withRowAnimation:UITableViewRowAnimationRight];
        break;

        case NSFetchedResultsChangeDelete:
             [tableView deleteSections:[NSIndexSet indexSetWithIndex:sectionIndex]
                      withRowAnimation:UITableViewRowAnimationLeft];
            break;
        case NSFetchedResultsChangeMove:break;
        case NSFetchedResultsChangeUpdate:break;
    }
}

- (void)controller:(NSFetchedResultsController *)controller didChangeObject:(id)anObject
       atIndexPath:(NSIndexPath *)indexPath forChangeType:(NSFetchedResultsChangeType)type
      newIndexPath:(NSIndexPath *)newIndexPath
{
     switch(type) {

        case NSFetchedResultsChangeInsert:
            [tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:newIndexPath] withRowAnimation:UITableViewRowAnimationLeft];
            break;

        case NSFetchedResultsChangeDelete:
            [tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationRight];
            break;

        case NSFetchedResultsChangeUpdate:
            [tableView reloadRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationNone];
            break;

        case NSFetchedResultsChangeMove:
            [tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationNone];
            [tableView insertRowsAtIndexPaths:[NSArray arrayWithObject:newIndexPath] withRowAnimation:UITableViewRowAnimationNone];
            break;
    }
}


- (void)controllerDidChangeContent:(NSFetchedResultsController *)controller
{
     [tableView endUpdates];
}

如何从数据数组中删除对象（核心数据）

2 个答案: