title: top navigation bar becomes visible when navigation back from push segue on iphone
body: <p>I'm hiding the navigationbar on a certain view, and when the user presses a button on the view, i'm <em>pushing</em> it to the next view. 
  In the next view, I am not longer hiding the nav bar and as expected it becomes visible. When hitting back however, the navbar on the first view also becomes (somehow) visible.</p>
  
  <p>I'm hiding the top navbar like this:</p>
  
  <pre><code>self.navigationController.navigationBar.hidden = YES;
  </code></pre>
  
  <p>And I'm making it visible like this:</p>
  
  <pre><code>self.navigationController.navigationBar.hidden = NO;
  </code></pre>
  
  <p>I wonder what could be wrong with this, as it's quite basic but somehow has a glitch.</p>