title: UIDocumentMenuViewController / UIDocumentPickerViewController slow to show in view
body: <p>I am trying to use the iOS file picker to select text files but when I instantiate and present (modally) a <code>UIDocumentMenuViewController</code> or a <code>UIDocumentPickerViewController</code> the UI takes a while to show up.</p>
  
  <p>This is the code I tried to use for the <code>UIDocumentMenuViewController</code> the one for the <code>UIDocumentPickerViewController</code> would be fairly similar:</p>
  
  <pre><code>    UIDocumentMenuViewController *menuVC = [[UIDocumentMenuViewController alloc] initWithDocumentTypes:@[(NSString *)kUTTypeText] inMode:UIDocumentPickerModeOpen];
  menuVC.delegate = self;
  [self presentViewController:menuVC animated:YES completion:nil];
  </code></pre>
  
  <p>If I try to call this code 3 or more times then the lag disappears.
  I understand that when working with iCloud documents there are synchronous operations that takes time but I didn't find a way to kind of preload that so by the time I present the view controller it happens instantly. I even tried to instantiate the view controllers much before presenting them, but  the initialisation doesn't seam to be the bottleneck.</p>
  
  <p>Did anyone experienced the same problem?</p>