title: Reseting navigation bar back button title to default iOS
body: <p>I know I can set the navigation bar back buttons's title with: </p>
  
  <pre><code>self.navigationItem.backBarButtonItem = UIBarButtonItem(title:"", style:.plain, target:nil, action:nil)
  </code></pre>
  
  <p>However there are parts of my app where <strong>I want to set it back to the default text "Back" (that will also use localization)</strong>. How would I go about doing this?</p>