title: How do I add back button to UINavigationBar programmatically?
body: <p>I have a UINavigationController and when I push one of my views, I have a UINavigationBar on top that I made an ivar for and connected it. Now what I need is that button that is like half square and half arrow on the left of the bar. How would I do this programmatically? All I need it to do is say back and do my back action when it is clicked. How would I do this?</p>
  
  <p>Thanks!</p>