TableView Cell reuse and unwanted checkmarks - this is killing me

Question

Apple\'s iOS TableView and cell reuse is killing me. I searched and searched and studied, but can\'t find good docs or good answers. The problem is that wh

Answer 1

cell reusing can be tricky but you have to keep 2 things in mind:

• Use one identifier for one type of cell - Using multiple identifiers is really only needed when you use different UITableViewCell-subclasses in one table view and you have to rely on their different behaviour for different cells
• The cell you reuse can be in any state, which means you have to configure every aspect of the cell again - especially checkmars / images / text / accessoryViews / accessoryTypes and more

What you need to do is to create a storage for your checkmark states - a simple array containing bools (or NSArray containing boolean NSNumber objects respectively) should do it. Then when you have to create/reuse a cell use following logic:

-(UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath
{
    static NSString *reuseIdentifier = @"MyCellType";
    UITableViewCell *cell = [tableView dequeueReusableCellWithIdentifier:reuseIdentifier];
    if(cell == nil) {
        /* create cell here */
    }
    // Configure cell now
    cell.textLabel.text = @"Cell text"; // load from datasource
    if([[stateArray objectAtIndex:indexPath.row] boolValue]) {
        cell.accessoryType = UITableViewCellAccessoryCheckmark;
    } else {
        cell.accessoryType = UITableViewCellAccessoryNone;
    }
    return cell;
}

then you will have to react on taps:

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
{
    [stateArray replaceObjectAtIndex:indexPath.row withObject:[NSNumber numberWithBool:![[stateArray objectAtIndex:indexPath.row] boolValue]]];
    [tableView reloadRowsAtIndexPaths:[NSArray arrayWithObject:indexPath] withRowAnimation:UITableViewRowAnimationFade];
}

Just remember to use NSMutableArray for your data store ;)