iOS: managing state between segues

Question

I'm working on an iPad app that has two controllers, a Login Controller and a View Controller. The Login Controller challenges the user for a username/password and once authenticated, there's a modal segue to the View Controller.

I've implemented a timeout wherein after 20 minutes of inactivity, the app segues back to the Login Controller. However, when the user logs back into the app, the state of the View Controller isn't preserved.

Is there a way to pass the View Controller object back to the Login Controller for re-use after logging into the app again? Is there a better way to manage the state?

Answer 1

Two possibilities come to mind...

You can create a model object either as a "singleton" or possibly owned by the application delegate and update it from the view controller and read from it whenever your view controller's view will appear.

The other option would be to have the view controller as the app's root controller and the login controller a modal overlay.

Answer 2

Your comment "Manage the state" is the answer you seek.

If there are changeable things about your view controller you'd like to save, then save them as they change, (either in NSUserDefaults, or CoreData, or some other persistent store) and have them populate when ViewController calls viewDidLoad.

Storing an entire UIViewController at the AppDelegate level just to preserve a handful of values is likely to be very wasteful, and won't help you at all if the app terminates. For this and many other reasons, your best bet is to follow MVC and make your model a persistent store which feeds the view.