title: Is there a notification on iOS if a UIAlertView is shown?
body: <p>Wondering if there is a notification available if a <code>UIAlertView</code> pops up?
  Background: my app asks the user for a PIN after a period of inactivity but I would like to prevent it if an alert is on screen.
  I don't want to go through my code and find all alerts and disable the PIN checker, instead a notification would be awesome. Any hope with <code>NSNotification</code>?</p>