title: Randomize two arrays the same way Swift
body: <p>I know there is a new shuffle method with <strong>iOS 9</strong>
  but I am wondering if there is anyway to shuffle two arrays the same way?</p>
  
  <p>For example</p>
  
  <pre><code>[1,2,3,4] and [a,b,c,d]
  shuffle
  [3,4,1,2] and [c,d,a,b]
  </code></pre>