title: addChildViewController and remove it
body: <p>In my project's main ViewController, once users of the app click the "Start" button, I add the next view to the screen:</p>
  
  <pre><code>UIViewController *nextController = [[GamePlayViewController alloc] initWithNibName:@"GamePlayView" bundle:nil];
  [self addChildViewController:nextController];
  [self.view addSubview:nextController.view];
  </code></pre>
  
  <p>Now, when users want to click back to the main menu, what is the proper code to run?</p>
  
  <p>I know I can transition from one viewController to another, like so:</p>
  
  <pre><code>[self transitionFromViewController:currentPageController 
                        toViewController:nextController 
                                duration:0 
                                 options:UIViewAnimationOptionTransitionCurlDown
                              animations:nil 
                              completion:^(BOOL finished) { [nextController didMoveToParentViewController:self]; }];
  </code></pre>
  
  <p>But what if I just want to transition back to the project's main ViewController?</p>
  
  <p>THANKS!</p>