swift - SKSpriteNode 未加载到屏幕上？

Question

一切正常，但是当我添加苹果时，它只在屏幕上停留很短的时间，然后它就消失/消失了。为什么是这样？任何帮助将不胜感激。

import SpriteKit

class GameScene: SKScene {
    var bg=SKSpriteNode()
    var apple=SKSpriteNode()
    override func didMoveToView(view: SKView) {
        /* Setup your scene here */
        let bg_texture=SKTexture(imageNamed: "wood-texture-pattern.jpg")
        bg=SKSpriteNode(texture: bg_texture)
        bg.position=CGPointMake(CGRectGetMidX(self.frame), CGRectGetMidY(self.frame))
        bg.size.height=self.frame.height
        bg.size.width=self.frame.width
        self.addChild(bg)
        let applePic=SKTexture(imageNamed:"apple.png")
        apple=SKSpriteNode(texture:applePic)
        apple.position=CGPointMake(CGRectGetMidX(self.frame),CGRectGetMidY(self.frame))
      //  apple.size.height=50
       // apple.size.width=50
        apple.setScale(0.25)
        self.addChild(apple)
    }

    override func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent?) {
       /* Called when a touch begins */


    }

    override func update(currentTime: CFTimeInterval) {
        /* Called before each frame is rendered */
    }
}

Answer 1

更改skspritenode的zPosition