我无法让我的球 SKSpriteNode 显示在辅助视图控制器的 UIImage(Xcode / Swift 2)

Question

我的第一个视图控制器上有一个按钮，指向第二个视图控制器。当第二个视图控制器出现时，应该会出现一个球图像，并且它的代码应该运行。我似乎在弄清楚为什么图像没有出现时遇到了一点麻烦。任何帮助将不胜感激！

---

import UIKit
import SpriteKit
class GameViewController: UIViewController {
    @IBOutlet weak var startButton: UIButton!
    override func viewDidLoad() {
        super.viewDidLoad()
        if let scene = gamePlay(fileNamed:"gamePlay") {
            // 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
            /* 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 .AllButUpsideDown
        } else {
            return .All
        }
    }
    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Release any cached data, images, etc that aren't in use.
    }
    override func prefersStatusBarHidden() -> Bool {
        return true
    }
}

---

import SceneKit
import SpriteKit
class gamePlayController: UIViewController {
}
class gamePlay: SKScene, SKPhysicsContactDelegate {
    let skyColor = SKColor(red: 0, green: 191, blue: 255, alpha: 1)
    var blueBall:SKSpriteNode!
    override func didMoveToView(view: SKView) {
        self.backgroundColor = skyColor
        self.physicsWorld.gravity = CGVectorMake(0.0, -5.0)
        self.physicsWorld.contactDelegate = self
        blueBall = SKSpriteNode( imageNamed: "ball")
        blueBall.position = CGPoint(x: CGRectGetMidX(self.frame), y: CGRectGetMidY(self.frame))
        blueBall.physicsBody = SKPhysicsBody(circleOfRadius: blueBall.size.width / 1.5 )
        blueBall.physicsBody!.dynamic = true
        blueBall.physicsBody!.allowsRotation = false
        self.addChild(blueBall)
    }
    override func touchesBegan(touches: Set<UITouch> , withEvent event: UIEvent?) {
        self.blueBall.physicsBody?.velocity = CGVectorMake(35, 0)
        self.blueBall.physicsBody?.applyImpulse(CGVectorMake(4, 10))
    } 
}

Answer 1

看起来位置不对。试试这个代码

        blueBall.position = CGPoint(x: CGRectGetMidX(self.bounds), y: CGRectGetMidY(self.bounds))

Answer 2

我解决了这个问题。我需要将我的 backgroundImage 编写为 SKSpriteNode，并相应地设置 zPosition。