title: popToRootViewController not working
body: <p>I have a <code>UIBarButtonItem</code> that I want to act as a logout button. When the user presses I want to <code>popToRootViewController</code> to take the user back to the login screen. When I call <code>popToRootViewController</code> nothing is happening. <code>self.navigationController</code> is not showing <code>nil</code> in print statements. I have a base view controller that all of my view controllers inherit from. I am attempting to have this logout functionality in the base view controller so all inherited view controllers don't need to also implement it. Is the fact that this is attempting to be implemented in base view controller a problem?</p>
  
  <pre><code>- (void)logoutBtnClicked {
      [self.navigationController popToRootViewControllerAnimated:YES];
      NSLog(@"nav: %@", self.navigationController);
  }
  </code></pre>
  
  <p>Also, the logoutBtnClicked is being called I know.</p>