title: popToViewController is not working but popViewController does
body: <pre><code>Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Tried to pop to a view controller that doesn't exist.'
  </code></pre>
  
  <p>When using this code</p>
  
  <pre><code>self?.navigationController?.popToViewController(vc2, animated: true)
  </code></pre>
  
  <p>But when I try to pop simply its working</p>
  
  <pre><code>self?.navigationController?.popViewController(animated: true)
  </code></pre>
  
  <p>I am pushing this viewController like </p>
  
  <pre><code>navigationController?.pushViewController(vc2, animated: true)
  </code></pre>
  
  <p>I am not sure, pushing a view means that when I try to do <code>popToViewController</code>. It has a view on top of it. Please help</p>