title: Get a BackButton on UINavigationBar saying 'Back' using localizations defined by iOS
body: <p>I have a <code>UINavigationBar</code> with two different screens. 
  On both screens the NavigationBar has the same title.
  So the BackButton should have just <code>Back</code> as text instead of the NavigationBar's title.</p>
  
  <p>If I set the parents ViewController title to <code>nil</code> I have a backButton with the text <code>Back</code>, which gets localized automatically by iOS.</p>
  
  <p>I know I can set the text to back as described in this question: <a href="https://stackoverflow.com/questions/2197698/how-to-set-the-text-of-a-back-button-on-a-uinavigationbar">How to set the text of a back button on a UINavigationBar?</a>
  However, then the <code>Back</code> is hardcoded and wont get translated by iOS automatically.</p>
  
  <p>I don't want to maintain the localizations by myself in the <code>Localizable.strings</code> but rather use the predefined values from iOS.</p>
  
  <p>I would like to always have a title on my NavigationBar and a backButton which says <code>Back</code> and gets localized automatically using the by iOS defined values. </p>
  
  <p>Does somebody know if and how such an behavior could be achieved?</p>