Question

I have a view which I use to add new records or edit existing ones. In viewWillAppear I load my record or just leave text fields blank.

I have a selection screen which is shown using pushViewController from the add / edit screen. Once I pick the value and return to my previous screen, viewWillAppear is called and the record is re-loaded and I loose any altered textfield values.

How should I keep values which are changed and currently lost ?

I think one question you’ll ask is, why don’t you load your record in viewDidLoad well the screen can be used a lot and it doesn’t get called every time the screen is shown.

Answer 1

Don’t rely on your views to save state. You should be saving changes to the data presented in your view into some form of model object(s). That way you can reload or recreate your view at any point and return it to the same state by repopulating it with the values found in a specific model.

This pattern is important because you want view controllers to be able to unload and reload their views as needed to reduce memory use. UIViewController does this automatically in response to a memory warning so if you assume that the view will still hold old data when it is not visible you’re going to lose that information.

In your case it sounds like you should be updating this record as you user changes values in your text fields. You can then reload the values from your record into your text fields in your -viewWillAppear: method.

Unfortunately I don’t know how to be more specific unless you show the code you are working on.