It is common knowledge that the UINavigationBar will display the previous UIViewController's title in an arrow shaped button at the left hand side corner. Basically if the previous UIViewController doesn't have a title the back button won't be visible as well.This is annoying and I always thought that the best practise would have been to have the button with the title "back". Following what I thought was a best practise Apple has introduced it in iOS 5. Good stuff :). But developers who want their app to work on previous iOS versions will still have to keep in mind the old practise.