title: How does the iOS app Display Recorder record the screen without using private API?
body: <p>The iOS app <a href="http://itunes.apple.com/us/app/display-recorder/id520411468?mt=8" rel="noreferrer">Display Recorder</a> claims to be able to record the screen of an iOS device, even while it is in the background. Given that <code>UIGetScreenImage()</code> is private API and will lead to a rejection on application submission when detected by the static analysis Apple runs, how were they able to do this recording in an approved application?</p>
  
  <p>Additionally, the app causes a red bar to appear at the top of the screen while it records, similar to the native iOS's phone call functionality.</p>
  
  <p>I've been an iOS developer for awhile, and I'm a bit stumped at how this was even done, even down to the detail of putting the red bar at the top when outside of the app.  I was under the impression we basically had no control of what's happening when the app runs in the background, short of some key pieces of functionality (like audio playing, etc).</p>
  
  <p>Even if the developer tapped into private API/libraries to accomplish this, how were they able to do this in a way that wasn't detected during review? My apologies if I'm missing something obvious that was introduced with a later version of iOS here.</p>