title: How to add navigation controller programmatically?
body: <p>In my app there is requirement that..I have 6 buttons in a nib,
  when I press any button a new nib will be loaded into the window according to the button pressed. problem is after loading the new nib If I want to come back to the previous nib (which is having all the buttons) how to add navigation controller?</p>
  
  <p>what I am doing now is while loading the new nib when I pressed the button</p>
  
  <pre><code>objNewViewController = [[NewViewController alloc] initWithNibName:@"NewViewController" bundle:nil];
  [self.navigationController pushViewController:objNewViewController animated:YES];
  </code></pre>
  
  <p>but by this way im not able to load the nib, it's not performing any operation?</p>