title: 'CGAffineTransformIdentity' is unavailable in Swift
body: <p>Came across this error when trying to do adapt some animations into Swift3 syntax. </p>
  
  <pre><code> UIView.animate(withDuration: duration, delay: 0.0, usingSpringWithDamping: 0.5, 
   initialSpringVelocity: 0.8, options: [] , animations: {
          fromView.transform = offScreenLeft
  
          toView.transform = CGAffineTransformIdentity
  
          }, completion: { finished in
              transitionContext.completeTransition(true)              
      })
  </code></pre>
  
  <p>and got this: </p>
  
  <blockquote>
    <p>'CGAffineTransformIdentity' is unavailable in Swift </p>
  </blockquote>