title: How to change the width of a CALayer with animation from left to right?
body: <p>I added a <code>CALayer</code> in a <code>UIView</code>.
  And it has a fillColor.
  It has also some width.
  I want that layer to expand it's  width from zero to actual width with <code>CABasicAnimation</code> from left to right direction.</p>
  
  <p>How to do that?  </p>