Crashes with completion handler in GameViewController - swift

Question

Want to preload textureAtlases before game starts, so I decided to put scene starter code into completion handler, but for some reason app crashes. Here is my code:
import UIKit
import SpriteKit
import GameplayKit
class GameViewController: UIViewController {
override func viewDidLoad() {
super.viewDidLoad()
let gpuAtlas = SKTextureAtlas(named: "GP")
let ppAtlas = SKTextureAtlas(named: "PP")
SKTextureAtlas.preloadTextureAtlases([gpuAtlas, ppAtlas]) {
if let view = self.view as? SKView {
let scene = GameScene(size: self.view.bounds.size)
// Set the scale mode to scale to fit the window
scene.scaleMode = .aspectFill
// Present the scene
view.presentScene(scene)
view.ignoresSiblingOrder = true
view.showsFPS = true
view.showsNodeCount = true
}
}
}
override var shouldAutorotate: Bool {
return true
}
override var supportedInterfaceOrientations: UIInterfaceOrientationMask {
return .portrait
}
override var prefersStatusBarHidden: Bool {
return true
}
}
If I remove preload texture atlas method everything will work as usual, but I want preload textures to have a change to get rid of first keyframe freeze because of loading textures in cache.
Error:
fatal error: unexpectedly found nil while unwrapping an Optional value
Update:
It crashes on GameScene.swift file in method didSimulatePhysics.
What I do wrong guys?

Answer 1

Try this (use main thread for manipulation with view and weak self):
SKTextureAtlas.preloadTextureAtlases([gpuAtlas, ppAtlas]) { [weak self] in
guard let gameView = self?.view as? SKView else { return }
DispatchQueue.main.async {
let scene = GameScene(size: gameView.bounds.size)
// Set the scale mode to scale to fit the window
scene.scaleMode = .aspectFill
// Present the scene
gameView.presentScene(scene)
gameView.ignoresSiblingOrder = true
gameView.showsFPS = true
gameView.showsNodeCount = true
}
}
Did you check if scene is optional? If so:
guard let scene = GameScene(size: gameView.bounds.size) else { return }

Answer 2

This
let gpuAtlas = SKTextureAtlas(named: "GP")
let ppAtlas = SKTextureAtlas(named: "PP")
SKTextureAtlas.preloadTextureAtlases([GP, PP]) {}
should not compile - the variables are named gpuAtlas and ppAtlas and not GP and PP.