title: UIView animation curve not working easeinout
body: <p>I am stumped by a very simple task, I want a UIView animation to do ease in / ease out but it is always linear despite using the correct animationOption.</p>
  
  <p>Here is the code which by all accounts should work, it's set in a UIViewControllerAnimatedTransitioning class but I have the same issue in a previous custom segue class;</p>
  
  <pre><code>[UIView animateWithDuration:0.4f delay:0.0f options:UIViewAnimationOptionCurveEaseInOut animations:^(void) {
  
          self.dimView.alpha = 1.0;
          self.imageView.frame = self.destinationRect;
  
      } completion:^(BOOL finished) {
  
          [self.imageView removeFromSuperview];
          [self.dimView removeFromSuperview];
  
          [transitionContext completeTransition:YES];
  
       }];
  </code></pre>
  
  <p>However, a spring animation with the following code works although I'd rather not do this.</p>
  
  <pre><code>[UIView animateWithDuration:0.8f delay:0 usingSpringWithDamping:0.7f initialSpringVelocity:2.0f options:UIViewAnimationOptionCurveEaseInOut animations:^(void) {
  
          self.dimView.alpha = 1.0;
          self.imageView.frame = self.destinationRect;
  
       } completion:^(BOOL finished){
  
          [self.imageView removeFromSuperview];
          [self.dimView removeFromSuperview];
  
          [transitionContext completeTransition:YES];
  
       }];
  </code></pre>
  
  <p>I'm getting the same behaviour on the simulator and on an iPad2 test device.
  Am I doing something wrong?
  Are there issues with animating either frame or alpha values?</p>