Presenting a scene in SpriteKit without discarding the previous?

Question

My situation is that I have a GameMenuScene and after the user chooses a level, I want to present the LevelScene. But I do not want to have the previous GameMenuScene discarded because the LevelScene is actually a @property of GameMenuScene and whether or not the user completes the level is to be saved as a @property of LevelScene, which the GameMenuScene should be able to access after the user finishes or exits the level. If I simply use presentScene:transition, the GameMenuScene is discarded and the information cannot pass back.

My question: Is there a way to stack or push the scenes on top of each other without discarding the previous (preferably using a transition animation)? I could not find a method for this specific purpose in the Apple Documentation for SKScene.

Note: Another StackOverflow answer to a similar question suggests to create a new UIViewController, present the LevelScene in there and then present the UIViewController modally. But I was hoping there was an existing method in the Apple Documentation that I have missed to present the scene itself scene modally without having to create UIVIewControllers.

Answer 1

There is no navigation controller-like capability for SKScenes that allows you to push and pop scenes. You will need to write code to manage and present your scenes.

Here's a simple view controller implementation that allows you to switch between two scenes (by swiping) without discarding the other scene.

@interface ViewController()

@property BOOL viewFlag;
@property SKScene *scene1;
@property SKScene *scene2;

@end

@implementation ViewController

- (void)viewDidLoad
{
    [super viewDidLoad];

    // Configure the view.
    SKView * skView = (SKView *)self.view;
    skView.showsFPS = YES;
    skView.showsNodeCount = YES;

    UISwipeGestureRecognizer *swipeGesture = [[UISwipeGestureRecognizer alloc]
                                              initWithTarget:self action:@selector(handleSwipeGesture:)];
    swipeGesture.direction = UISwipeGestureRecognizerDirectionRight;
    [self.view addGestureRecognizer:swipeGesture];

    // Create and configure scene 1.
    SKScene * scene = [MyScene sceneWithSize:skView.bounds.size];
    scene.scaleMode = SKSceneScaleModeAspectFill;

    self.scene1 = scene;

    // Present the scene 1.
    [skView presentScene:scene];

    // Create and configure scene 2.
    scene = [MySecondScene sceneWithSize:skView.bounds.size];
    scene.scaleMode = SKSceneScaleModeAspectFill;

    self.scene2 = scene;
}

- (void) handleSwipeGesture:(id)sender
{
    SKView * skView = (SKView *)self.view;
    _viewFlag = !_viewFlag;
    if (_viewFlag) {
        [skView presentScene:_scene1];
    }
    else {
        [skView presentScene:_scene2];
    }
}

@end