title: NSCFSet objectAtIndex unrecognized selector, iterating works
body: <p>I was wondering how it can be that iterating through an NSMutableArray works, but when I call objectAtIndex it fails with "*** -[NSCFSet objectAtIndex:]: unrecognized selector sent to instance 0x..."</p>
  
  <p>Here is some sample code, the program is too big to share in whole so I hope it's enough. The code is executed in the latest iPhone Simulator from XCode. </p>
  
  <pre><code>- (UITableViewCell *)tableView:(UITableView *)tableView cellForRowAtIndexPath:(NSIndexPath *)indexPath {
   RDLogString(@"Creating cell @ row no. %d", indexPath.row);
   CPPlayerAppDelegate * appDelegate = [[UIApplication sharedApplication] delegate];
   RDLogString(@"Conversations: %p. Item count: %d", appDelegate.distribution.conversations, appDelegate.distribution.conversations.count);  
   //This works  
   for(CPConversation * x in appDelegate.distribution.conversations){
    RDLogString(@"Pointer: %p with name %@", x, x.name);
   }  
   //This fails with aforementioned error  
   CPConversation * conversationAtCurrentIndex = [appDelegate.distribution.conversations objectAtIndex: indexPath.row];
  </code></pre>
  
  <p>Sorry for the bad formatting, still figuring it out. :)</p>
  
  <p>Thanks in advance,
  Nick</p>