title: Use default back button in navigation controller
body: <p>I don't know how to make a navigation controller use the default <code>&lt;</code> button. The only way I know how to add a back button at all is to add a <code>Bar Button Item</code> but there I have to provide the image myself. I want to use the default system back symbol, the kind that shows up with show/push segue. Is this possible?</p>