title: Sort array of objects into ascending order
body: <p>I have an array of objects. Each object has a key "username".</p>
  
  <p>Is there a swift way of sorting this array of objects into ascending order?</p>
  
  <pre><code>(array(at: indexPath.row) as AnyObject).value(forKey: "username") as? String)!
  </code></pre>
  
  <p>Thanks</p>