SKSpriteNode寬度隨着變量增加而不會減少？

Question

我已經設置了SKSpriteNode作爲進度/健康狀態欄。 寬度設置爲一個變量。 這個變量隨着定時器的減少而減少，但節點的寬度並沒有減少？ 如果我設置變量增加，那麼節點寬度增加沒有問題，但是如果我設置變量減少不起作用。 我擔心我在這裏犯了一個簡單的錯誤。 這裏是工作的代碼，但如果我改變+不起作用=來= -

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

要添加新的精靈不刪除舊的每次更新。過了一段時間，你會有許多精靈在彼此之上。新的精靈將會縮短，但舊的精靈仍然在展示，所以酒吧似乎並沒有縮短。

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) 
    } 
}