title: animateKeyframesWithDuration not persisting
body: <p>I am using <code>animateKeyframesWithDuration:delay:options:animations:completion:</code> which adjusts (moves) the frame of several views. However, when the animation completes the views revert to their original location - like the results of the animation are not persisting.</p>
  
  <p>Here is the affected code:</p>
  
  <pre><code>UIView.animateKeyframesWithDuration(0.5, delay: 0, options: .CalculationModeCubic, animations: {
              UIView.addKeyframeWithRelativeStartTime(0.0, relativeDuration: 0.5) {
  
                  //Moving main View
                  tappedView.frame = CGRectMake((self.screenSize.width/2)-250, (self.screenSize.height/2)-250, 500, 500)
  
                  //Centering other views
                  tappedImage.frame = CGRectMake(185.5, 10, 129, 129)
                  tappedTitle.frame = CGRectMake(100, 149, 300, 33)
                  tappedShort.frame = CGRectMake(125, 175, 250, 85)
                  tappedDetail.frame = CGRectMake(20, 230, 460, 135)
                  tappedClose.frame = CGRectMake(370, 477, 128, 21)
  
  
              }
          }, completion:nil)
  </code></pre>
  
  <p>I have tried including a completion hander which sets the frame at their final location:</p>
  
  <pre><code>{(finished: Bool) -&gt; Void in
  
              tappedImage.frame = CGRectMake(185.5, 10, 129, 129)
              tappedTitle.frame = CGRectMake(100, 149, 300, 33)
              tappedShort.frame = CGRectMake(125, 175, 250, 85)
              tappedDetail.frame = CGRectMake(20, 230, 460, 135)
              tappedClose.frame = CGRectMake(370, 477, 128, 21)
  
          }
  </code></pre>
  
  <p>which does work, but results in a flicker - like there is a slight delay between when the animation ends (and it starts reverting to the original location) and when the completion handler fires.</p>
  
  <p>Any help appreciated.</p>