Question

This may be impossible, but I’m trying to save the state of my application between scene transitions, but I can’t figure out what to do. Currently I love the way that when you have an application running and hit the home button, you can go back to that application just where you left off, but if you transition between scenes (in a storyboard), once you get back to that scene the application state was not saved.

I only have two different scenes that need to be saved (you transition back and forth from one to the other). How can I go about saving a storyboard scenes state without taking up precise memory?

More Detailed: Here is my entire storyboard. You transition back and forth between scenes using the plus toolbar button. On the second scene the user can tap on the table view cells and a real image will fill the image view (See figure 1.2)

Figure 1.1

In figure 1.2 you see what happens when you tap inside one of the many table view cells (an image view pops up.)

Figure 1.2

THE PROBLEM: When you tap a table view cell, which fills an image view (shown in figure 1.2) it works fine if you stay on that scene or even hit the iPhone home button (if you hit the iPhone home button and then reopen the app the scene’s state was saved and the image view filled with a simple image still shows just like we left it), but if I transition (using the plus button) back to the first scene, and then use the plus button on the first scene to get back to the second scene the image view that I created (shown in figure 1.2) disappears and the second scene loads without saving the state and image views we filled.

EDIT: I tried using the same view controller for both scenes, but it didn’t solve the problem.

UPDATE: I just found the following code (that I think stores a views state). How could I use this and is this what I’ve been looking for?

MyViewController *myViewController=[MyViewController alloc] initWithNibName:@"myView" bundle:nil];
[[self navigationController] pushViewController:myViewController animated:YES];
[myViewController release];

Answer 1

I would suggest a combination of two things:
1. Take DBD‘s advice and make sure that you don’t continuously create new views
2. Create a shared class that is the data controller (for the golfers, so that the data is independent of the scene)

The correct way to make the segues would be to have one leading from the view controller on the left to the one on the right. However, to dismiss the one on the right you can use

-(IBAction)buttonPushed:(id)sender 
      [self dismissModalViewControllerAnimated:YES];
}

This will take you back the the view controller on the left, with the view controller on the left in its original state. The problem now is how to save the data on the right.

To do this, you can create a singleton class. Singleton classes have only one instance, so no matter how many times you go to the view controller on the right, the data will always be the same.

Singleton Class Implementation (Of a class called DataManager) – Header

@interface DataManager : NSObject {
}

+(id)initializeData;
-(id)init;
@end

Singleton Class Implementation (Of a class called DataManager) – Main

static DataManager *sharedDataManager = nil;

@implementation DataManager
+(id)initializeData {
    @synchronized(self) {
        if (sharedDataManager == nil)
            sharedDataManager = [[self alloc] init];
    }
    return sharedDataManager;
}

-(id)init { 
    if(self == [super init]) {
    } 
    return self;
}
@end

Then, inside your view controller code you can grab this instance like this

DataManager *sharedDataManager = [DataManager initializeDataManager];

This way you will have the same data no matter how many times you switch views.
Also, you can better adhere to MVC programming by keeping you data and your view controllers separate. (http://en.wikipedia.org/wiki/Model–view–controller)