I want to be able to set the font of my apps navigation bar back button without doing anything too crazy and without losing any other design characteristics of the button (i
Swift version of the all mentioned above (excerpt from the original answer) :
let customFont = UIFont(name: "customFontName", size: 17.0)!
UIBarButtonItem.appearance().setTitleTextAttributes([NSFontAttributeName: customFont], forState: .normal)
More goodies:
https://stackoverflow.com/a/28347428/469614