title: iOS animating a view including subviews
body: <p>I'm trying to make an animation for collapsing a view which includes some subviews.</p>
  
  <pre><code>[UIView beginAnimations:@"advancedAnimations" context:nil];
  [UIView setAnimationDuration:3.0];
  
  CGRect aFrame = aView.frame;
  aView.size.height = 0;
  aView.frame = aFrame;
  
  [UIView commitAnimations];
  </code></pre>
  
  <p>This animation is doing fine, but for the aView only. Subviews doesn't collapse as expected.
  How do I make the subviews collapsing as well? Furthermore, is there a way to recalculate original size after collapsing?</p>
  
  <p>THX</p>