SKSpriteNode 宽度随变量增加但不会减少？

Question

我已经将 SKSpriteNode 设置为 progress/health 栏。宽度设置为变量。这个变量随着计时器的增加而减少，但是节点的宽度并没有随之减少？如果我将变量设置为增加，则节点宽度增加没有问题，但是如果我将变量设置为减少，则节点宽度增加则不起作用。我担心我在这里犯了一个简单的错误。这是有效的代码，但如果我将 += 更改为 -=

则不起作用

class GameScene: SKScene, SKPhysicsContactDelegate {

var health = SKSpriteNode()
var healthTimer = Timer()
var progressValue = 350


func startHealthTimer() {

    progressValue += 20

}


override func didMove(to view: SKView) {

    healthTimer = Timer.scheduledTimer(timeInterval: 1, target: self, selector: #selector(self.startHealthTimer), userInfo: nil, repeats: true)

}


override func update(_ currentTime: TimeInterval) {

    let healthTexture = SKTexture(imageNamed: "health.png")
    health = SKSpriteNode(color: .white, size: CGSize(width: progressValue, height: 30))
    health.position = CGPoint(x: -self.frame.width / 2 + healthTexture.size().width / 2, y: self.frame.height / 2)
    health.zPosition = 2
    self.addChild(health)

}

Answer 1

每次更新您都会添加一个新精灵，而不会删除旧精灵。一段时间后，您会看到许多精灵相互叠加。新精灵会更短，但旧精灵仍在显示，所以条形图不会变短。

class GameScene: SKScene, SKPhysicsContactDelegate {

    var health: SKSpriteNode?
    var healthTimer = Timer()
    var progressValue = 350

    func startHealthTimer() {
        progressValue += 20
    }

    override func didMove(to view: SKView) {
        healthTimer = Timer.scheduledTimer(timeInterval: 1, target: self, selector: #selector(self.startHealthTimer), userInfo: nil, repeats: true)
    }

    override func update(_ currentTime: TimeInterval) {
        if let health = self.health {
            health.removeFromParent()
        }

        let healthTexture = SKTexture(imageNamed: "health.png")
        self.health = SKSpriteNode(color: .white, size: CGSize(width: progressValue, height: 30))
        self.health.position = CGPoint(x: -self.frame.width / 2 + healthTexture.size().width / 2, y: self.frame.height / 2)
        self.health.zPosition = 2
        self.addChild(self.health)
    }
}

SKSpriteNode 宽度随变量增加但不会减少？

SKSpriteNode width increases with variable but won't decrease?

progress

ios

sprite-kit

swift