title: Delay when updating the background of a UIButton
body: <p>I'm using setBackgroundImage:forState: to update the background of a UIButton. The background is updated but only after a few seconds. There is obviously some refresh cycle at work here but I can't find exactly what the problem is. I've tried to play with setNeedsRefresh and setNeedsDisplay without any result.</p>
  
  <p>How can I change the UIButton background instantaneously ?</p>
  
  <p>Thanks</p>