title: Can the size of a stretchable button image be animated in Cocoa Touch?
body: <p>I'm creating a UIButton with a <strong>stretchableImageWithLeftCapWidth:topCapHeight:</strong></p>
  
  <p>I would like to change it's size smoothly with Core Animation like so:</p>
  
  <pre><code>float shrinkFactor = 0.2;
  NSTimeInterval slowSpeed = 5.0;
  
  [UIView beginAnimations:nil context:nil];
  [UIView setAnimationDuration:slowSpeed];
  
  UIButton *thisButton = (UIButton *)[self.view viewWithTag:2];
  thisButton.frame = CGRectMake(thisButton.frame.origin.x, thisButton.frame.origin.y, buttonStretchedWidth * shrinkFactor, thisButton.frame.size.height);
  
  [UIView commitAnimations];
  </code></pre>
  
  <p>The button image size doesn't animate, it just snaps to the new size. </p>
  
  <p>When I make the <strong>backgroundColor</strong> of the button visible, I see the frame itself animates correctly.</p>
  
  <p>Am I missing something or is the image stretching not animatable?</p>