title: Move text in UITextField with animation
body: <p>I need to move <code>text</code> in <code>UITextField</code> (from right to left, and then back) with animation like in <em>Safari App in iOS 7</em> (see the screenshots below).
  Is there any way to do it?
  I know that I can set <code>textAlignment</code>, but it won't be animated.</p>
  
  <p>Maybe I should change <code>leftView</code> size in <code>UITextField</code>? But I'm not sure how to calculate size, when text should be aligned on the center. Please, help.~</p>
  
  <p><a href="https://i.stack.imgur.com/UEw6d.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/UEw6d.jpg" alt="1"></a><br>
  <sub>(source: <a href="http://cs424818.vk.me/v424818291/70fa/y7JW2_RKPnA.jpg" rel="nofollow noreferrer">cs424818.vk.me</a>)</sub>  </p>