CODEWITHSUNDEEP
iosvariablesmodalviewcontrollerdismiss
gluon
gluon

Reputation: 662

Dismissing a view makes losing it all values... viewWillAppear as a cure?

I have a basic modal view system.

My app loads the UI base in which there are 2 buttons presenting 2 other views. In those views, a dismiss button.

Everything works fine.

BUT, in one of the 2 modal views, I have a bunch of UISlider & UISwitch. I want them to retain their values but the dismiss loses them: as soon as I trigger the button to show the view containing the UI elements, this view is shown with all values for all elements as I put initially in the xib.

should I store all values in variables, then in viewWillAppear I could "recall" them ?

would you advice me another strategy ?

Upvotes: 0

Views: 154

Answers (2)

matt
matt

Reputation: 536028

Yes, your proposed approach is exactly the right sort of thing. But be careful; viewWillAppear can be called for many reasons; make sure you're only doing this when the view controller is coming into existence and showing the view for the first time.

NSUserDefaults can be an excellent place to store globally needed info like this. In viewWillDisappear, store the desired state info (values of the sliders and switches) in defaults. Then retrieve them the next time the view is about to appear.

Upvotes: 2

Justin Paulson
Justin Paulson

Reputation: 4388

When you create the modal view you are creating a new instance of the modalViewController an the modalView. This new instance knows nothing about any other instance. There are a few ways you can retain the information from previous iterations of these modal view controllers.

How I would do it: Set up place holders in your main view and pass the values that the user selects back to the main view via a protocol and delegate setup. Then when you segue to the modal view you can load those variables in before displaying the modal view.

So let's say you have a dictionary with all of the values: {slider = YES, someValue=10,...} Create that dictionary in the main view controller, the first one that opens, and place some default values in it.

In your modal view controllers create the same dictionary as a property.

Create a protocol in your modal view controller with a method that is something like

- (void) doneEditing:(NSDictionary *)values

Set up your first view as the delegate for the modal view controller and in the implementation of doneEditing copy the values to the dictionary that is present in the first view before popping the modal view.

When the first view is ready to present the modal view again, copy the values to the dictionary property of the modal view before presenting it.

I hope this gets you headed in the right direction. It's important to remember that each time you segue or create and present a modal view you are creating a brand new instance of that view, it knows nothing about the previous instance at all unless you tell it something about it.

Upvotes: 2

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