Update NSUserDefaults data in one ViewController changed in other ViewController

Question

I got two viewcontroller: MainController and OptionsController. OptionsController it can be reached through a button from MainController. In OptionsController is there some values that I can save with NSUserDefaults. These values are needed in MainController. If I change these values in OptionsController when I come back to MainController they don’t change, but if I launch MainController again, these values was changed correctly. It seems that when MainController becomes active again, after leaving OptionsController, viewDidLoad is no longer raised. How can I update the data in MainController, please?

Answer 1

As rounak says, viewDidLoad is only called once in the life of a view controller. If you have code you want executed every time a view controller is shown, put it in viewWillAppear.

NSUserDefaultsis a fairly heavyweight way to pass info between in-memory objects (it writes to disk). If you don't need persistence between runs, one of the other options he suggested would be better. I'd suggest the delegate pattern or a completion block.

Answer 2

viewDidLoad is called only once for a view controller. You can use NSNotification, KVO, blocks or something like a delegate pattern to get a callback in your MainController whenever the value changes inside the OptionsController.

You can otherwise write code in viewWillAppear which gets called each time you pop the options controller.