title: How to switch between two view controllers
body: <p>I have two <code>UIViewControllers</code>, vc1 and vc2. </p>
  
  <p>I want to switch between them. But before loading the view of the new view controller, I want to destroy/release/remove (I'm not sure abt the correct word to use here) the previous viewcontroller. </p>
  
  <p>For example, when I am switching to vc2 from vc1 ,I want to destroy vc1 completely, so that when I return to vc1 from vc2, vc1 will be loaded from scratch (i.e. <code>viewDidLoad</code> will be executed).</p>
  
  <p>Which type of view switching should I opt for?</p>
  
  <ol>
  <li>presentModal... </li>
  <li>addSubview. </li>
  </ol>
  
  <p>I am not using a navigation controller.  </p>
  
  <p>Currently I am using the presentModal... method, but when I use <code>dismissModalViewcontroller</code> on the newly presented view controller, it doesn't show up a new instance of the previous view controller. Instead, it shows the already running instance of it. </p>
  
  <p>I want the <code>viewDidLoad</code> method of the previous view controller to run when I dismiss the newly presented view controller.</p>