title: blocking user interaction with underlying views
body: <p>In my app, i have an overlay view, which is displayed when some processing and networking is happening. It is just a semitransparent view (subclass of UIView) with a loading indicator on it, filling the whole screen.</p>
  
  <p>I want to prevent any of the underlying views to recieve user-interaction (e.g. a underlying table view should not be scrolled, a button not be pressed).</p>
  
  <p>What is the best way i can do this from within the overlay view?</p>