DropCharge causing memory leak

📚 Official Books 2D iOS & tvOS Games by Tutorials
1

I make the DropCharge game by following the book. After I finish, I go ahead and check the memory pane of the Debug Navigator, I found out that the memory is constantly going higher and higher every time, and when the game is over, pressing restart to open a new scene doesn’t free up any memory. Seems like something is making a retain cycle. Any idea or running into similar issue? Thanks.

2

While you’re in the simulator you will be emulating the 3D hardware in the phone and even on a fast Mac that can cause some serious performance issues. Give it a try on the actual hardware… I was amazed at how slow and how much memory was being consumed when trying some SpriteKit programming on the simulator, in fact I thought my app had serious issues where in fact it was fine.

3

There is memory leak because we don’t remove the off screen background node and the foreground overlays.

Found it yesterday and fixed like this:

func isOffScreen(node: SKNode) -> Bool {
    var isOffScreen = false
    
    let cameraPos = self.getCameraPosition()
    if node.position.y + self.backHeight < cameraPos.y {
        isOffScreen = true
    }
    
    return isOffScreen
}

func removeOffScreenBackgroundNode() {
    bgNode.enumerateChildNodesWithName("Overlay") { (node, _) -> Void in
        if self.isOffScreen(node) {
            node.removeFromParent()
        }
    }
}

func removeOffscreenOverlayNode() {
    for node in fgNode.children {
        if isOffScreen(node) {
            node.removeFromParent()
        }
    }
}
4

As of june 2020, swift 5 iOS 13.5, I have updated the method “updateLevel” based on @ivanchenhz solution. When overlays are added in the scene, check every “Overlay” nodes out of camera and remove them. I am quite new to swift so please let me know if this is the wrong way to “fix” the issue.

First, let’s see the issue :

  • set to true view.showsFPS and view.showsNodeCount in GameViewController.swift
  • set an insane amount of gain in setPlayerVelocity(_: ) to very quickly add new layers
func setPlayerVelocity(_ amount:CGFloat) 
{
 let gain: CGFloat = 100
 player.physicsBody!.velocity.dy = max(player.physicsBody!.velocity.dy, amount * gain)
}

Quickly, the amount of nodes is above 10K, 15K, 20K, too much K and FPS goes from 60fps to almost 0

Now, let’s remove nodes not needed anymore since they will never be visible again

func updateLevel() 
{
 let cameraPos = camera!.position
 if cameraPos.y > levelPositionY - size.height 
 {
  createBackgroundOverlay()
  while lastOverlayPosition.y < levelPositionY 
  { 
   addRandomForegroundOverlay() 
  }

  // Start fix here, remove off screen nodes
  enumerateChildNodes(withName: "//Overlay")
  {
   [weak self] node, _ in
   guard let self = self else { return }

   let cameraPos = self.camera!.position
   if node.position.y + self.backgroundOverlayHeight < cameraPos.y
   {
    node.removeFromParent()
   }
  }
 // End fix 
 }
}

Now, the nodes count stay in an acceptable range 150…250 and FPS stay at 60fps

I hope it can be of any help.

5

And when you read further the latest book version (as of june 2020), you have the required code to address the issue at the end of chapter 17 section IV. I might have read the whole chapter before trying to fix the issue by myself :stuck_out_tongue:

// remove old foreground nodes...
for fgChild in fgNode.children {
  let nodePos = fgNode.convert(fgChild.position, to: self)
  if !isNodeVisible(fgChild, positionY: nodePos.y) {
    fgChild.removeFromParent()
  }
}
6

@mokhet Thank you for sharing this - much appreciated!

7

Hi…I’m additionally encoutering this equivalent memory spill. For my situation CGDataProviderCreateWithCopyOfData is made everytime I take pictures with my photograph application. This article will at that point endure in memory after I take various photographs until I get an out of memory blunder. In the event that I utilize the “Holes” Xcode Instrumentation apparatus, it focuses to AVCapturePhotoOutput - init similar to the wellspring of the memory spill. I’m utilizing xcode 12 beta 3/4 however I’ve likewise given this a shot a couple of different adaptations of iOS and I get a similar outcome (ie iOS 10.2, 11.4, 12 b3). Would you be able to if it’s not too much trouble, direct me toward a guide that would help in settling this.