title: Swift 3 UIView animation
body: <p>Since upgrading my project to swift 3 my autolayout constraint animations aren't working; to be more specific, they're snapping to the new position rather than animating.</p>
  
  <pre><code>UIView.animate(withDuration: 0.1,
                 delay: 0.1,
                 options: UIViewAnimationOptions.curveEaseIn,
                 animations: { () -&gt; Void in
                     constraint.constant = ButtonAnimationValues.YPosition.DefaultOut()
                     self.layoutIfNeeded()
      }, completion: { (finished) -&gt; Void in
      // ....
  })
  </code></pre>
  
  <p>I know they added the <code>UIViewPropertyAnimator</code> class but am yet to try it.</p>