Question

I want Checkmark in particular TableView Cell.

So I have used code :

- (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath {

newRow = [indexPath row];
oldRow = [lastIndexPath row];

if (newRow != oldRow) {
    UITableViewCell *newCell = [tableView cellForRowAtIndexPath:indexPath];
    newCell.accessoryType = UITableViewCellAccessoryCheckmark;

    UITableViewCell *oldCell = [tableView cellForRowAtIndexPath: lastIndexPath]; 
    oldCell.accessoryType = UITableViewCellAccessoryNone;

    lastIndexPath = indexPath; 
}
else{
    UITableViewCell *newCell = [tableView cellForRowAtIndexPath:indexPath];
    newCell.accessoryType = UITableViewCellAccessoryCheckmark;
    lastIndexPath = indexPath;
}}

Its working in iPhone Simulator fine.
But while testing in iPhone device, it crashes the application.

Any solution for this..?

Thanks in advance.

Answer 1

The most likely cause of your crash is in your ivar, lastIndexPath. You’re storing values in this without retaining them, so they may be released at any time. Try defining a property named lastIndexPath (retain for manual reference counting, strong for automatic reference counting). Then you can use self.lastIndexPath = indexPath or [self setLastIndexPath:indexPath].

Also, it’s bad to forcibly change a cell contents like this. It’s better to store the selected index, then reload the table data. For maximum efficiency, only update the changed cells. Have your cellForRowAtIndexPath: method switch the checkmarks on and off.