title: Incorrect Class type when loading a UIViewController from Storyboard
body: <p>I have a <code>UIViewController</code> in my storyboard for which I have set my own custom class <code>MyCustomClass</code> (that extends <code>UIViewController</code>) </p>
  
  <p>This view controller has a button in it and I show a <code>UIAlertView</code> upon a tap on this button. Simple? Here is my issue:</p>
  
  <p>I get:</p>
  
  <pre><code>Unknown class MyCustomClass in Interface Builder file.
  </code></pre>
  
  <p>When I push the view controller to the <code>UINavigationController</code>:</p>
  
  <pre><code>MyCustomClass *vc = [story instantiateViewControllerWithIdentifier:@"MyCustomClassView"];
  NSLog(@"receiver's type: %@", NSStringFromClass([vc class]));
  </code></pre>
  
  <p>Which causes the app to crash when I tap the button inside this view controller. Any reason why that might be happening?</p>