title: UIView.animateWithDuration not working
body: <p>I am making a messaging app. When the keyboard is shown, I want the UITextField to move up along with it, just as it does in the Messages app. However, my animation call is not working. It does not animate the textInputView as it should, but still calls the completion block after:</p>
  
  <pre><code>func keyboardWasShown(aNotification: NSNotification)
  {
      var info = aNotification.userInfo! as Dictionary&lt;NSObject,AnyObject&gt;
      var kbSize = info[UIKeyboardFrameEndUserInfoKey]?.CGRectValue().size
  
      UIView.animateWithDuration(0.2, animations: { () -&gt; Void in
  
          self.textInputView.frame.origin.y = self.view.frame.height - self.textInputView.frame.height - kbSize!.height
  
  
          println("Should move textInputView to: \(self.textInputView.frame.origin.y)") 
  
          }) { (bool) -&gt; Void in
  
  
              println("Location of textInputView.frame.origin.y after animation: \(self.textInputView.frame.origin.y)")
  
      }
  }
  </code></pre>
  
  <p>When I run this code, it prints:</p>
  
  <p>Should move textInputView.frame.origin.y to: 297.0</p>
  
  <p>Location of textInputView.frame.origin.y after animation: 521.0</p>
  
  <p>Why is it not animating?</p>