删除最后一条记录时UITableView deleteRowsAtIndexPath崩溃

Question

当我从a中删除最后一条记录时遇到以下错误UITableView.

由于未捕获的异常'NSInternalInconsistencyException'而终止应用程序,原因:'无效更新:第0节中的行数无效.更新后的现有部分中包含的行数(3)必须等于该行中包含的行数在更新(1)之前的部分,加上或减去从该部分插入或删除的行数(插入1个,删除1个)并加上或减去移入或移出该部分的行数(0移入,0移动)出)."

如果表数组为空,我的目标是显示"No Record found".

这是我正在使用的代码.当我从表数组中删除最后一条记录时,应用程序崩溃了.如何重新加载表并显示"No Record Found"标签？

// Customize the number of rows in the table view.
- (NSInteger)tableView:(UITableView *)tableView numberOfRowsInSection:(NSInteger)section {
    if ([idArray count]==0) {
        return  3;
    }
    else 
    {
        return [idArray count];
    }   
}

// Customize the appearance of table view cells.
- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {

    NSLog(@"array count %d",[idArray count]);
    if ([idArray count] == 0) {
        static NSString *CellIdentifier = @"Cell";

        UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
        if (cell == nil) {
            cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier];
        }
        cell.textLabel.textAlignment = UITextAlignmentCenter;

        tableView.userInteractionEnabled = NO;

        self.navigationItem.leftBarButtonItem.enabled = NO;
         NSUInteger row = [indexPath row];

        switch (row) {
            case 0:
                cell.textLabel.text = @"";
                break;
            case 1:
                cell.textLabel.text = @"";
                break;

            case 2:
                cell.textLabel.text = @"No Records Found";
                break;


            default:
                break;
        }        

        return cell;
    }
    else
    {   static NSString *CellIdentifier = @"Cell";

        UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifier];
        if (cell == nil) {
            cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleSubtitle reuseIdentifier:CellIdentifier];
        }

        tableView.userInteractionEnabled = YES;

        self.navigationItem.leftBarButtonItem.enabled = YES;

        // Set up the cell
        identify *idItems = [idArray objectAtIndex:indexPath.row];

        NSDateFormatter *formatter = [[NSDateFormatter alloc] init];
        [formatter setDateFormat:@"dd MMM,yyyy"];
        NSString *dateStr = [formatter stringFromDate:idItems.Date];
        UIImageView *accDis = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"Arrow.png"]];    
        cell.accessoryView = accDis;
        self.idTableView.separatorColor = [UIColor colorWithRed:150.0/255.0 green:150.0/255.0 blue:150.0/255.0 alpha:1];
        cell.textLabel.textColor = [UIColor blackColor];
        cell.textLabel.font = [UIFont boldSystemFontOfSize:18];
        cell.textLabel.adjustsFontSizeToFitWidth = YES;
        cell.detailTextLabel.textColor = [UIColor colorWithRed:100.0/255.0 green:100.0/255.0 blue:100.0/255.0 alpha:1];
        cell.detailTextLabel.font = [UIFont italicSystemFontOfSize:16];
        cell.detailTextLabel.adjustsFontSizeToFitWidth = YES;

        NSString *detailText = [NSString stringWithFormat:@"%@ - %@",dateStr,idItems.GeoCode];

        if (idItems.Image == NULL) {
            cell.imageView.image = [UIImage imageNamed:@"icon58x58.png"];
        }
        else
        {
        //pass image to fix size 50 X 50
        //UIImage *newImage = [self postProcessImage:idItems.Image];
            cell.imageView.image = idItems.thumb;//newImage; 
        cell.imageView.contentMode=UIViewContentModeScaleAspectFill;
        }

        cell.textLabel.text = idItems.TypeName; 
        cell.detailTextLabel.text = detailText;

        return cell;   
    }    
}

- (void)tableView:(UITableView *)tv commitEditingStyle:(UITableViewCellEditingStyle)editingStyle 
    forRowAtIndexPath:(NSIndexPath *)indexPath {

    if(editingStyle == UITableViewCellEditingStyleDelete) {

        if ([idArray count] >=1) 
        {
            [idTableView beginUpdates];

            //Get the object to delete from the array.
            identifyObject = [appDelegate.idArray objectAtIndex:indexPath.row];

            //Delete the object from the table.
            [self.idTableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
             [appDelegate removeID:identifyObject];

            if ([idArray count] == 0) {
                [self.idTableView insertRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
            }
            [idTableView endUpdates];
        }
    }
}

Answer 1

问题是tableview期望在视图上执行的操作与数据源匹配.表中有一条记录,您将其删除.tableview期望数据源现在包含零记录,但由于你的"没有找到记录"逻辑,它实际上返回值3,因此出现一致性错误,以及崩溃.

这个bug似乎就是这个部分:

if ([idArray count] == 0) {
    [self.idTableView insertRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
}

我假设这是为了在删除最后一行时将"找不到记录"行插入表中,但由于你的"没有找到记录"实际上跨越三行,你需要在这里插入三行,如下所示:

if ([idArray count] == 0) {
    [self.idTableView insertRowsAtIndexPaths:[NSArray arrayWithObjects:
    [NSIndexPath indexPathForRow:0 inSection:indexPath.section],
    [NSIndexPath indexPathForRow:1 inSection:indexPath.section],
    [NSIndexPath indexPathForRow:2 inSection:indexPath.section],
    nil] withRowAnimation:UITableViewRowAnimationFade];
}

然而,对于你自己的理智,我可以建议一个不同的方法吗？为什么不将这些假的三行数据同时用于显示目的,而不是试图保持你的表和数据源同步,为什么不只是将UILabel插入你的视图层次结构(在tableview的前面或后面),说"没有找到记录"并根据表格是否有任何数据显示/隐藏它？这样,您可以精确控制其位置和外观,而无需使用数据源逻辑.

Answer 2

处理删除行的一般规则是:

1. 处理你的模特
2. 处理行的动画

例如:

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

   if (editingStyle == UITableViewCellEditingStyleDelete) {
       NSInteger row = [indexPath row];

       [yourModel removeObjectAtIndex:row]; // you need to update your model

       [tableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath]    withRowAnimation:UITableViewRowAnimationFade];
    }
}

现在,在我看来,正确的代码可以是以下(我写了一些评论来指导你).

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

    if (editingStyle == UITableViewCellEditingStyleDelete) {
        //Get the object to delete from the array.
        identifyObject = [appDelegate.idArray objectAtIndex:indexPath.row];
        [appDelegate removeID:identifyObject]; // update model first

        // now you can check model count and do what you want
        if ([appDelegate.idArray count] == 0) // I think you mean appDelegate.idArray
        {   
            // do what you want
            // with  [self.idTableView insertRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
        }

        else
        {
            [self.idTableView deleteRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
        }
    }
}

希望能帮助到你.