title: UIDocumentInteractionControllerDelegate check when document is loaded
body: <p>Which delegate function of <code>UIDocumentInteractionControllerDelegate</code> is called when document is completely loaded on the preview?<br>
  Just to share, I have already tried : </p>
  
  <pre><code>- (void)documentInteractionControllerDidEndPreview:(UIDocumentInteractionController *)controller  
  </code></pre>
  
  <p>And this is called when we close the preview.</p>