小故障/错误与滚动表视图

Question

I'm getting a weird glitch / bug with my UITableView. Everything load up fine, however, when I scroll down to the second cell and back to the first, the label's text in the first cell becomes the same as in the second cell… I'm not really sure why this is happening can you kindly look at my code and help me out.

Code

- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    NSString *CellIdentifer = [NSString stringWithFormat:@"CellIdentifier%i",num];
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:CellIdentifer];

    if (cell == nil)
    {
        cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifer];
    }

    UILabel *titleL = [[UILabel alloc] initWithFrame:CGRectMake(10,10,300,20)];
    titleL.text = myTitle;

    [cell addSubview:titleL];

    return cell;
}
-(void) makeMeADreamer {
    for (int i = 0; i < arr.count; i++) {
        PFQuery *query = [PFQuery queryWithClassName:@"DreamBits"];
        [query whereKey:@"objectId" equalTo:[arr objectAtIndex:i]];

        [query getFirstObjectInBackgroundWithBlock:^(PFObject *object, NSError *error) {
            if (!object) {
            } else {
                myTitle = [object objectForKey:@"title"];
                num = i;
                [feed beginUpdates];
                [feed reloadRowsAtIndexPaths:myArr withRowAnimation:UITableViewRowAnimationAutomatic];
                [feed endUpdates];
            }
        }];
    }
}

Answer 1

Try to replace this code:

UILabel *titleL = [[UILabel alloc] initWithFrame:CGRectMake(10,10,300,20)];
    titleL.text = myTitle;

    [cell addSubview:titleL];

to the willDisplayCellForRowAtIndexPath: method. Your have the same label text in both cells because your second cell is dequeued from first cell with all its subviews.

- (UITableViewCell*)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
     static NSString* cellId = @"messagesCell";
     UITableViewCell* cell = [tableView dequeueReusableCellWithIdentifier:cellId];
     if (!cell)
         cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:cellId];

     return cell;
}

- (void)tableView:(UITableView *)tableView willDisplayCell:(UITableViewCell *)cell forRowAtIndexPath:(NSIndexPath *)indexPath
{
    UILabel *titleL = [[UILabel alloc] initWithFrame:CGRectMake(10,10,300,20)];
    titleL.text = myTitle;

    [cell addSubview:titleL];
}

Answer 2

You create the tableViewCell in the wrong way. You create a label and add it into the cell each time the table view reload. So you may see many label if you scroll down and up. You should only create one label and re-use it. Try the following code

if (cell == nil)
{
    cell = [[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifer];
    UILabel *titleL = [[UILabel alloc] initWithFrame:CGRectMake(10,10,300,20)];
    titleL.tag = 1234;
    [cell.contentView addSubview:titleL];
}

UILabel *titleL = (UILable*)[cell.contentView viewWithTag:1234];
titleL.text = myTitle;