title: uitextfield animate width constraint
body: <p>I have this code to animate a width constraint of a UITextField</p>
  
  <pre><code>self.myTextFieldWidthConstraint.constant = 200
  UIView.animateWithDuration(2, delay: 0.0, options: UIViewAnimationOptions.CurveLinear, animations: { () -&gt; Void in
      self.viewContainer.layoutIfNeeded()
  }, completion: nil)
  </code></pre>
  
  <p>It works fine, the only issue is that if there is text inside the text field, during the animation it shrinks in character width and then re-adjusts to the correct size. The placeholder text does not have the same issue.</p>
  
  <p>Here is a gif: <a href="http://makeagif.com/mr4u1D" rel="noreferrer">http://makeagif.com/mr4u1D</a></p>