title: Going back to initial storyboard ViewController on logout
body: <p>I am using storyboards in my iOS. The first screen is the login screen. When a user logs out or gets logged out, he may be on a screen in a deep hierarchy. </p>
  
  <p>For example: login view controller => modal view controller => tab bar controller => nav controller => view controller => view controller. I want to go all the way back from the top-most view controller to the bottom one.</p>
  
  <p>Edit: Here's a diagram of the view hierarchy:<img src="https://i.stack.imgur.com/IGcpA.png" alt="enter image description here"></p>
  
  <p>Thanks!</p>