title: Add a border outside of a UIView (instead of inside)
body: <p>If a add a border of a view using code in a view like</p>
  
  <pre><code>self.layer.borderColor = [UIColor yellowColor].CGColor;
  self.layer.borderWidth = 2.0f;
  </code></pre>
  
  <p>the border is added inside the view like the following:
  <img src="https://i.stack.imgur.com/bhbts.png" alt="enter image description here"></p>
  
  <p>the right view is the original view, as you can see, the black area of bordered view is less than the original one. but what I want to get is a border outside of original view, like this:<img src="https://i.stack.imgur.com/yZj7C.png" alt="enter image description here">. the black area is equal to original one, how can I  implement it?</p>