I have an iPad app (XCode 4.6, iOS 6.2, ARC and Storyboards with a UITabController). The setup scene is the first scene displayed if required data is missing; I don't want the user to be able to leave that scene unless all required fields have valid data in them.
The only place I can think of is validating the presence of data while in -viewWillDisappear; however at that point it's too late to not change to the scene that the user tapped. It is possible for the user to tap another tab, thereby bypassing all of the existing validation.
Anybody have any ideas on how to prevent going to another scene if the required data is missing?