title: UIView transitionWithView animating property change: slide in from right?
body: <p>I have a readonly UITextView, and I'm updating the text.
  When the new text appears, I want it to animate as follows: New text slides in from the right, as the old text slides offscreen toward the left side.</p>
  
  <p>Is it possible to do this with transitionWithView? If not, what's the best way to do it? I can make it do a CrossDissolve, but that's not the animation I'm looking for:</p>
  
  <pre><code>    [UIView transitionWithView:self.storyTextView
                    duration:0.5
                     options:UIViewAnimationOptionTransitionCrossDissolve
                  animations:^{
                      [self.storyTextView setText:withStory.storyText];
                  }
                  completion:nil];
  </code></pre>
  
  <p>The reason for insisting on the right to left animation is because eventually I want the user to be able to trigger it by swiping toward the left on the UITextView.</p>