代码之家 › 专栏 › 技术社区 › maddie

在调用“DeleteRowstIndepaths:withRowAnimation”之前删除对象仍会生成:无效更新:第0节中的行数无效

uitableview objective-c ios

maddie · 技术社区 · 7 年前

问题是,用户在调用之前忽略了从数据数组中删除对象 deleteRowsAtIndexPaths:withRowAnimation reloadData 然后 deleteRowsAtIndexPaths:withRowAnimation .

但是,我确实从数据源中删除了该对象(a) NSFetchedResultsController )通话前 deleteRowsAtIndexPaths:withRowAnimation . 我不打电话 .

- (void)tableView:(UITableView *)tableView commitEditingStyle:(UITableViewCellEditingStyle)editingStyle forRowAtIndexPath:(NSIndexPath *)indexPath
{
    /*Only allow deletion for collection table */
    if(_segmentedControl.selectedSegmentIndex == 1) {
        NSLog(@"delete ca");
        if (editingStyle == UITableViewCellEditingStyleDelete)
    {
        CollectedLeaf* collectedLeaf = [collectionFetchedResultsController objectAtIndexPath:indexPath];
        LeafletPhotoUploader * leafletPhotoUploader = [[LeafletPhotoUploader alloc] init];
        leafletPhotoUploader.collectedLeaf = collectedLeaf;

        if([LeafletUserRegistration isUserRegistered]) {
            [leafletPhotoUploader deleteCollectedLeaf:collectedLeaf delegate:self];
        }


        // Delete the managed object for the given index path
        NSManagedObjectContext *context = [collectionFetchedResultsController managedObjectContext];
        [context deleteObject:[collectionFetchedResultsController objectAtIndexPath:indexPath]];

        // Save the context.
        NSError *error;
        if (![context save:&error])
        {
            NSLog(@"Failed to save to data store: %@", [error localizedDescription]);
            NSArray* detailedErrors = [[error userInfo] objectForKey:NSDetailedErrorsKey];
            if(detailedErrors != nil && [detailedErrors count] > 0)
            {
                for(NSError* detailedError in detailedErrors)
                {
                    NSLog(@"  DetailedError: %@", [detailedError userInfo]);
                }
            }
            else 
            {
                NSLog(@"  %@", [error userInfo]);
            }
        }

    [tableView deleteRowsAtIndexPaths:@[indexPath] withRowAnimation:UITableViewRowAnimationAutomatic];
    }

    }

}

无效更新:节0中的行数无效。数量更新(2)后现有节中包含的行必须为更新(2),加上或减去从中插入或删除的行数该部分(插入0,删除1)加上或减去移入或移出该节的行(0移入,0移出)。

而不是 .

虽然它解决了错误,但表单元格并没有真正被删除,您可以通过仍然存在的“Collected:null”标签看到:

此viewcontroller有一个分段控件,其索引更改加载到表中的数据。数据从 NSFetchedResultsController

if(_segmentedControl.selectedSegmentIndex == 1) {
       /// [_table removeFromSuperview];
        _search_bar.hidden=YES;

        UIImage *btnImage2 = [UIImage imageNamed:seg2_buttonImg];
        [_left_button setImage:btnImage2 forState:UIControlStateNormal];
        NSError *error;
        [self.collectionFetchedResultsController performFetch:&error];
        [self collectionFetchedResultsController];
        collectedLeafArray = [collectionFetchedResultsController fetchedObjects];
        [_table reloadData];
    }

因此,以下是我对numberOfRowsInSection的实现:

- (NSInteger) tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section{

    if(_segmentedControl.selectedSegmentIndex == 0){
        id <NSFetchedResultsSectionInfo> sectionInfo = [[speciesFetchedResultsController sections] objectAtIndex:section];

        return [sectionInfo numberOfObjects];
    }
    id <NSFetchedResultsSectionInfo> sectionInfo = [[collectionFetchedResultsController sections] objectAtIndex:section];
    return [sectionInfo numberOfObjects];
}

删除行后,如何更新collectionFetchedResultsController的计数?

1 回复 | 直到 7 年前

maddie 7 年前

I found a solution here . 基本上我是在打电话 deleteRowsAtIndexPaths:withRowAnimation 在数据源有时间完成删除之前。

对于其他正在努力修改UITableView的人,这里有一个委托方法来处理它,并 here is the Apple documentation it was taken from

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

    UITableView *tableView = self.tableView;

    switch(type) {

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

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

        case NSFetchedResultsChangeUpdate:
            [self configureCell:[tableView cellForRowAtIndexPath:indexPath]
                atIndexPath:indexPath];
            break;

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