title: shouldPerformSegueWithIdentifier not working with SWRevealViewController
body: <p>I am trying to prompt an alert and request payment for premium features in my app before a segue happens, but <code>shouldPerformSegue</code> doesn't seem to be working. I have a <code>SWRevealViewController</code> that opens a side menu, from which I connected the segue manually in my Storyboard. I clicked the Segue and named identified it.</p>
  
  <pre><code>override func shouldPerformSegueWithIdentifier(identifier: String, sender: AnyObject?) -&gt; Bool {
      if identifier == "advanced_segue" {
          purchaseRequest()
          print("shouldPerformSegue working")
          return false
      } else {
      return true }
  }
  </code></pre>
  
  <p>Please see attached picture. <a href="https://i.stack.imgur.com/5FiXP.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/5FiXP.png" alt="Example in Timeline"></a></p>