Swift，SpriteKit：释放一个Gamescene并重新分配一个新的

我需要在玩家完成一个关卡后释放playcene，以便内存可用于加载我游戏的另一个级别 . 如果我不这样做，我的应用程序崩溃是因为内存问题 .

我遵循了那里的指示：

Swift: Deallocate GameScene after transition to new scene?

但不幸的是，它对我不起作用 . 我在GameViewController类中收到错误“无法将值'UIView'转换为'SKView' . 这是我的整个代码：

import Foundation
import UIKit
import SpriteKit

class GameViewController: UIViewController {

    var scene1: SKScene?
    var scene2: SKScene?
    var scene3: SKScene?
    var skView: SKView?


    func nextSceneAction1() {

        scene2 = nil
        scene3 = nil

        skView! = self.view as! SKView
        skView!.showsFPS = true
        skView!.showsNodeCount = true

        /* Sprite Kit applies additional optimizations to improve rendering performance */
        skView!.ignoresSiblingOrder = true

        scene1 = TransitionSigns(size: skView!.frame.size)
        scene1!.size.width = 2048
        scene1!.size.height = 1536


        /* Set the scale mode to scale to fit the window */
        scene1!.scaleMode = .AspectFill

        let transition = SKTransition.revealWithDirection(.Right, duration: 2)

        scene1!.scaleMode = .AspectFill
        skView!.presentScene(scene1!, transition: transition)
    }

    func nextSceneAction2() {

        scene1 = nil
        scene3 = nil

        let skView = self.view as! SKView
        skView.showsFPS = true
        skView.showsNodeCount = true

        /* Sprite Kit applies additional optimizations to improve rendering performance */
        skView.ignoresSiblingOrder = true

        scene2 = TransitionSigns(size: skView.frame.size)
        scene2!.size.width = 2048
        scene2!.size.height = 1536


        /* Set the scale mode to scale to fit the window */
        scene2!.scaleMode = .AspectFill

        let transition = SKTransition.revealWithDirection(.Right, duration: 2)

        scene2!.scaleMode = .AspectFill
        skView.presentScene(scene2!, transition: transition)
    }

    func nextSceneAction3() {

        scene1 = nil
        scene2 = nil

        let skView = self.view as! SKView
        skView.showsFPS = true
        skView.showsNodeCount = true

        /* Sprite Kit applies additional optimizations to improve rendering performance */
        skView.ignoresSiblingOrder = true

        scene3 = TransitionSigns(size: skView.frame.size)
        scene3!.size.width = 2048
        scene3!.size.height = 1536


        /* Set the scale mode to scale to fit the window */
        scene3!.scaleMode = .AspectFill

        let transition = SKTransition.revealWithDirection(.Right, duration: 2)

        scene3!.scaleMode = .AspectFill
        skView.presentScene(scene3!, transition: transition)
    }


    override func viewWillLayoutSubviews() {
        // Configure the view.

        let skView = self.view as! SKView
        skView.showsFPS = true
        skView.showsNodeCount = true

        /* Sprite Kit applies additional optimizations to improve rendering performance */
        skView.ignoresSiblingOrder = true

        let scene = MainView(size: skView.frame.size)
        scene.size.width = 2048
        scene.size.height = 1536

        /* Set the scale mode to scale to fit the window */
        scene.scaleMode = .AspectFill

        skView.presentScene(scene)
    }

    override func shouldAutorotate() -> Bool {
        return true
    }

    override func supportedInterfaceOrientations() ->   UIInterfaceOrientationMask {
        if UIDevice.currentDevice().userInterfaceIdiom == .Phone {
            return UIInterfaceOrientationMask.AllButUpsideDown
        } else {
            return UIInterfaceOrientationMask.All
        }
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Release any cached data, images, etc that aren't in use.
    }

    override func prefersStatusBarHidden() -> Bool {
        return true
    }


    override func viewDidLoad() {
        super.viewDidLoad()

    }

    override func viewDidDisappear(animated: Bool) {

        self.view.removeFromSuperview()
    }

    override func viewWillDisappear(animated: Bool){
        self.view.removeFromSuperview()
    }
}

我从其他类调用不同的函数 nextSceneAction1() ， nextSceneAction2() 和 nextSceneAction3() ：

let controller1 = GameViewController()
controller1.nextSceneAction1()

要么

let controller2 = GameViewController()
controller2.nextSceneAction1()

加载新场景时，我收到此错误：“无法将'UIView'类型的值转换为'SKView' . 你知道这段代码有什么问题吗？

顺便说一句，在开启新场景之前，我打开所有其他可能性来清理旧场景，以便在应用程序的生命周期内没有内存崩溃 .