Sprite Kit memory issues

[gershengoren]

Hello,

first of all – thank you for 2D iOS and tvOS Games by Tutorials book – it is really helpfull

So I created a small game with several scenes and facing some memory issues:

• The first issue I already solved – a scene was not deallocated after transition to another scene. I didn’t have any strong references inside of this scene, but the deinit was simply not called at all. I present a scene like in the tutorial:

    if let scene = GameScene(fileNamed:"GameScene") {
        let transition = SKTransition.crossFadeWithDuration(1.0)
        scene.scaleMode = .AspectFill
        scene.backgroundColor = SKColor.redColor()
        self.view?.presentScene(scene, transition: transition)
    }
  

  So I solved this by overriding willMoveFromView. In this method I iterate through all nodes and remove they from parent node. I also stop all actions and remove them. Finally I call removeFromParent() method. After this the deinit method is called when I present the next scene. This approach was not obvious for me, because it is not used in the tutorials and there are no issues with memory usage.

• Though all scenes and nodes are being deallocated now (I just added debugPrint("\(NSStringFromClass(self.dynamicType)).deinit") in deinit method of each custom class to double check whether deinit is called), I still have a memory issue when I simply switch between two scenes (simply scenes with 3-4 sprite nodes) and each scene presents the next one like mentioned above:
  
  Even when I simply stay in one scene the memory usage increases:
  

  
  
  So I tried to find memory leaks with Instruments and there are some of them (at this point I simply display a start scene with couple of buttons and two basic animations):
  
  
  
  It seems like the problem is in MetalKit, but I don’t know how to fix this and which part of my game causes this issue.

Do you have any advices where I can start searching?
Thanks

[gershengoren]

It seems like skView.showsPhysics = true caused continuous memory consumption growth. After I removed this line the mentioned memory leaks were also gone.

The issue I still have – memory is not completely freed after scene is deallocated. After I switch between two scenes several times I get following:

I also tried to invoke memory warning in simulator, but nothing happened.

[jgnovak]

Are you usking SKActions to play sound effects by chance?

[gershengoren]

I think there were a couple of things that prevented memory of being deallocated. But I solved this memory issue finally. Changes I made:

• SKTexture(imageNamed:) → SKTexture(image:) (when I can’t use an atlas)
• double check all closures and pass weak or unowned self
• remove all actions, delegates, and child-nodes etc. in willMoveFromView function of the scene
• remove all components from GKComponentSystem in willMoveFromView function
• replace all SKAction.playSoundFileNamed with runBlock actions which start AVAudioPlayer

[einharch]

For my part, the main culprit is the SKTexture(imageNamed:), this loads a texture into memory and doesn’t deallocate it even if the node is removed from the scene.
You have to manually re-remove all nodes from the scene (in whichever function that signals the exit of the actual scene), and then set the scene to nil.

I wrote a small loop-function that just loops through childs and remove every node, after that setting the scene to nil and doing another presentScene: (presenting an empty scene forces the current one to deallocate).
This solved my memory leak problems.

If you have a predefined number of nodes, you can reset their textures to an empty image as well.

[jzt5061]

@gershengoren Can you show some of your code for your willMoveFromView function? I’m running into some of the same problems.