title: Flipping a circular UIView
body: <p>I'm working on a project that has circular views that flip over. </p>
  
  <p>So far, I've tried a couple of the solutions provided here on SOflow:</p>
  
  <ul>
  <li>simply rounding the corners of the view's layer.</li>
  <li>creating a custom CircleView that sets <code>backgroundColor</code> to <code>[UIColor clearColor]</code> and manually drawing the circle on in <code>drawRect</code>.</li>
  </ul>
  
  <p>In each case, when the view flips to the new view, it's a rectangular portion of the screen that flips, not just the circle. I'd like the flip to just be the circle, but I'm not sure where to go next.</p>
  
  <p>Here's the method I'm using to flip the view currently:</p>
  
  <pre><code>-(void)changeSpotToView:(SpotView *)toView {
      [UIView transitionFromView:self.activeView
                          toView:toView
                        duration:1.0
                         options:UIViewAnimationOptionTransitionFlipFromTop
                      completion:^(BOOL finished) {
                          self.activeView = toView;
                      }];
  
  }
  </code></pre>
  
  <p>The container the <code>SpotView</code>s are in is also a <code>SpotView</code>, so it should be just a circle as well.</p>
  
  <p>Any guidance would be appreciated!</p>