title: Push View Controller into Navigation Controller
body: <p>Some times when I push ViewController into Navigation Controller,
  the viewDidLoad() method of the View Controller is not called.
  And this cause my application to crash. I would appreciate any help.</p>
  
  <p>I forget to mention that I load the view from the nib before I push it to the Navigation Controller. </p>
  
  <p>Thanks,
  Sarah  </p>