title: How can I change the backBarButtonItem colour in Swift?
body: <p>I am trying to change the default backBarButtonItem colour to white colour,</p>
  
  <p>my codes look like below</p>
  
  <pre><code>self.navigationItem.backBarButtonItem?.tintColor = UIColor.whiteColor()
  </code></pre>
  
  <p>But It is not working for me, any ideas?</p>