title: How can I dismiss a UINavigationController presented modally?
body: <p>I have the following structure:</p>
  
  <pre><code>UINavigationController(1) -&gt; MainViewController     ---PRESENT MODAL---&gt; 
  UINavigationController(2) -&gt; TutorialViewController ---PRESENT MODAL---&gt; LoginViewController
                                                      ---PRESENT MODAL---&gt; SignupViewController
  </code></pre>
  
  <p>I want to dismiss the UINavigationController(2) from a user action on LoginViewController.</p>
  
  <p>Any idea?</p>