title: Activity Indicator and Cancel button
body: <p>When I tap button app create network request. I want to show activity indicator and I want have possibility of stop this request, so I want cancel button. I can add activity indicator to alert view, but Apple say "The UIAlertController class is intended to be used as-is and does not support subclassing. The view hierarchy for this class is private and must not be modified."
  What is the right UI for this situation?</p>