Properly get rid of old SKScene?

Question

I have a few problems in my game and I think I found the source. First of all, I use a CMMotionManager in my game to capture gyro motion, and if the user plays the game twice without closing the app completely first, the gyro can glitch and stop listening to the user, probably because there are two gameScene's, so there are two CMMotionManagers. I also have music playing in the menu that I have to explicitly call stop on when I transition to the gameScene, and it should just be deallocating that scene.

I don't want to deal with multiple view controllers, so my idea is:

1. Pass the old scene as an argument into the new scene
2. Once the new scene has loaded, set the old scene to nil

Should this solve my problems?

Answer 1

Calling SKView presentScene: or presentScene:transition: will properly get rid of old SKScene.

However, if there is a strong reference to the old scene, that scene will not be deallocated. My experience of this problem was from Trial and Error.

Please check this code post. It demos when the scene has a weak reference or a strong reference. https://gist.github.com/naterhat/5399eec40eaa23edbfbc

Without seeing your code, my suggestion to solve the problem is by removing any connection to the scene other than SKView. Log when scene suppose to be deallocated by switching to a new scene. If works, then slowly connect new code. If not deallocated, something is still referencing the old scene.

You can check in Instruments to see if a scene is deallocated. Instead, I find it best to do this by adding logs in the init and dealloc methods of the scene.

- (void)dealloc
{
    NSLog(@"%@ Scene DEALLOCATED", self.name);
}

- (instancetype)initWithSize:(CGSize)size
{
    if(self = [super initWithSize:size]){
        self.name = @"TEST";
        NSLog(@"%@ Scene CREATED", self.name);
    }
}

Hope this helps.