title: NSButtonCell checkbox inside NSTableView is always getting NSOffState. Why?
body: <p>Hi guys I'm new to Cocoa programming and I am getting always NSOffState whether I'm checking or unchecking an NSButtonCell (Check Box Cell in the UI dragged to a cell in an NSTableView).
  I have a @property IBOutlet NSButtonCell *mySelection, connected to the respective UI and the following code.</p>
  
  <pre><code>- (void) tableView:(NSTableView *)tableView setObjectValue:(id)object forTableColumn:(NSTableColumn *)tableColumn row:(NSInteger)row
  {
  MediaAComparar *media = [mediasRecesEnStock objectAtIndex:row];
  NSString *identifier = [tableColumn identifier];
  
  if ([identifier isEqualToString:@"seleccion"])
  {
      if ([mySelection state] == NSOnState)
      {
          [media setValue:object forKey:@"seleccion"];
          NSLog(@"on state");
      }
  
      if ([mySelection state] == NSOffState)
      {
         [media setValue:object forKey:@"seleccion"];
          NSLog(@"off state");
  
      }
  
  }
  
  }
  </code></pre>
  
  <p>I never get the NSOnState to execute, the only NSLog message I get is: off state.
  Can anyone give me some help?
  Thanks!!</p>