Question

Below is code for UITableView, But when i scroll its behaves weirdly (too annoying)… This problem is due to reuseIdentifier…. but dont know how to solve..

- (UITableViewCell *)tableView:(UITableView *)tableView1 cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    static NSString *CellIdentifier = @"Cell";

    UITableViewCell *cell = [tableView1 dequeueReusableCellWithIdentifier:CellIdentifier];

    NSInteger imgTag = 1;
    NSInteger lblTag = 2;

    if (cell == nil) {
        cell = [[[UITableViewCell alloc] initWithStyle:UITableViewCellStyleDefault reuseIdentifier:CellIdentifier] autorelease];
        cell.selectionStyle = UITableViewCellSelectionStyleNone;

        UIImageView *imgView = [[UIImageView alloc] initWithFrame:CGRectMake(2, 2, 52, 52)];
//        Image:[UIImage imageNamed:[self.glassType objectAtIndex:indexPath.row]]];
        imgView.tag = imgTag;
        [cell.contentView addSubview:imgView];
        [imgView release];

        UILabel *lblName = [[UILabel alloc] initWithFrame:CGRectMake(60, cell.frame.size.height/4, 200, 21)];
//        lblName.text = [self.glassName objectAtIndex:indexPath.row];
        lblName.tag = lblTag;
        [cell addSubview:lblName];
        [lblName release];
    }

    NSInteger imgIndex = 2;
    NSInteger lblIndex = 3;

    ((UIImageView *)[cell viewWithTag:imgTag]).image = [[self.glassType objectAtIndex:indexPath.row] objectAtIndex:imgIndex];
    ((UILabel *)[cell viewWithTag:lblTag]).text = [[self.glassName objectAtIndex:indexPath.row] objectAtIndex:lblIndex];

    return cell;
}

- (void)tableView:(UITableView *)tableView1 didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
    UITableViewCell *cell = [tableView1 cellForRowAtIndexPath:indexPath];
    cell.accessoryType = UITableViewCellAccessoryCheckmark;
}

How to make Cell for row at index so that it remains constant even when scrolled??? Also how to make single selection in UITableView??

Answer 1

The answer is that you should not add subviews to your table cells outside of the “if (cell == nil) { …” clause or they get added over and over again to the same cell when it gets re-used.

See my answer to this question for a more detailed explanation, including code for how to fix it:

cellForRowAtIndexPath memory management

You also cannot store state in table cells because as soon as they scroll offscreen they are recycled and re-appear at a different index in your table. You need to set up an array of model objects to store state for your table cells (such as what their accessory type should be). A more detailed explanation can be found in my answer to this question:

Looping through UITableViewCells of a UITableView

If you fix how you are adding subviews to the cells, and store your “ticked” state in an array of model objects as well as setting the cell.accessoryType (so that it can be restored when the cell is dequeued), then your approach to row selection is otherwise correct.

So put this in your tableView:cellForRowAtIndexPath: method, just before the return cell;:

MyModelObject *object = [self.arrayOfModelObjects objectAtIndex:indexPath.row];
BOOL isChecked = object.checked;
cell.accessoryType = isChecked? UITableViewCellAccessoryCheckmark: UITableViewCellAccessoryNone;

And in your tableView: didSelectRowAtIndexPath: method, get rid of the current logic and replace it with:

- (void)tableView:(UITableView *)tableView1 didSelectRowAtIndexPath:(NSIndexPath *)indexPath
    for (int i = 0; i < [self.arrayOfModelObjects count]; i++)
    {
        MyModelObject *object = [self.arrayOfModelObjects objectAtIndex:i];
        object.checked = (i == indexPath.row); // only check the one we just tapped
    }

    //refresh table to update the accessory views for all rows
    [tableView1 reloadData];
}

Obviously replace the arrayOfModelObjects with your own model implementation. You could just use an array of NSNumber objects containing bools if you don’t want to create a custom class for this purpose.