In Etude (etudeapp.com), I made a custom nav bar class and a custom back button control, and I just hijack -pushNavigationItem:animated: in the custom nav bar.
For what it's worth, I really think it damages the ecosystem when apps fake standard SDK classes and make them do strange things, like what Instagr.am is doing. Those standard classes are there and have limitations for a reason.<p>I really don't like what instagr.am has done to the UINavigationBar and there's a lot of applications out there that tries to hijack known standards to make them crazy stuff.
The title is a tiny bit misleading. The one on the article is better.<p>I was confused at first because he's reinventing UINavigationBar, not custom back buttons - back buttons are occasionally part of that reinvention, however.