title: How to iterate all the UIViewControllers on the app
body: <p>I have a xib with this structure:</p>
  
  <pre><code>- Tab Bar Controller
  -- Tab Bar
  -- NavigationController
  --- Navigation Bar
  --- News List View Controller
  ---- Navigation Item
  --- Tab Bar Item
  
  -- NavigationController
  --- Navigation Bar
  --- News List View Controller
  ---- Navigation Item
  --- Tab Bar Item
  -- NavigationController
  --- Navigation Bar
  --- News List View Controller
  ---- Navigation Item
  --- Tab Bar Item
  [...]
  </code></pre>
  
  <p>How can I code a loop to take each UIViewController (News List View Controller) in each iteration?</p>