title: Disable action items in UIDocumentInteractionController's presentPreviewAnimated
body: <p>I am using UIDocumentInteractionController's presentPreviewAnimated method to preview document.  It works fine.  But I wish to disable the action button while in the preview mode. I have the following two delegated methods to return NO.  But these two methods never got called at all.  The other delegated methods work fine.  Any suggestion?</p>
  
  <pre><code>-(BOOL)documentInteractionController:(UIDocumentInteractionController *)controller canPerformAction:(SEL)action {
  NSLog(@"canPerformAction");
  return NO;
  }
  </code></pre>
  
  <p>and</p>
  
  <pre><code>-(BOOL)documentInteractionController:(UIDocumentInteractionController *)controller performAction:(SEL)action {
  NSLog(@"performAction");
  return NO;
  }
  </code></pre>