title: preferredStatusBarStyle is not working
body: <p>I used to use <code>setStatusBarStyle</code> in my project and it works fine, but it is deprecated so I use <code>preferredStatusBarStyle</code>, that didn't work. 
  knowing that I've:</p>
  
  <ol>
  <li>Call the method setNeedsStatusBarAppearanceUpdate.</li>
  <li>Set "View controller-based status bar appearance" to NO in info.plist</li>
  <li><p>Override the function</p>
  
  <ul>
  <li>(UIStatusBarStyle)preferredStatusBarStyle
  {
  return UIStatusBarStyleLightContent;
  }</li>
  </ul>
  
  <p>this function is not called</p></li>
  </ol>
  
  <p><em>Note</em>: I'm using navigation controller.</p>