title: NSNotificationCenter Code works in iPhone but not on iPad
body: <pre><code>[[NSNotificationCenter defaultCenter] addObserver:self 
                                        selector:@selector(didEnterBackground:)
                                        name:UIApplicationDidEnterBackgroundNotification
                                        object:nil];
  </code></pre>
  
  <p>Why does this code work on iPhone simulator but not on iPad simulator? I get <code>EXC_BAD_ACCESS</code> on this code. Tried version iOS 3.2, 4.2, 4.3.</p>