斯威夫特：暫停CABasicAnimation的CALayer的

Question

你看到下面的代碼創建一個CALayer的（長方形），從左至右動畫（您可以直接複製和粘貼代碼在新的項目）：

 //Global Variables 
var layer = CALayer() 
var holdGesture = UILongPressGestureRecognizer() 
let animation = CABasicAnimation(keyPath: "bounds.size.width") 


func setUpView(){ 

    self.view.addGestureRecognizer(holdGesture) 
    holdGesture.addTarget(self, action:"handleLongPress:") 

} 


func handleLongPress(sender : UILongPressGestureRecognizer){ 

    //NEED IT HERE 
    //var layer = CALayer() 

    layer.frame = CGRect(x: 0, y: 0, width: 0, height: 10) 
    layer.backgroundColor = UIColor.redColor().CGColor 

    animation.fromValue = 0 
    animation.toValue = self.view.bounds.width * 2 
    animation.duration = 5 
    self.view.layer.addSublayer(layer) 

    if(sender.state == .Began){ 
     print("Long Press Began") 
     layer.addAnimation(animation, forKey: "bounds.size.width") 
    } 


    else{ 
     print("Long press ended") 
     pauseLayer(layer) 
    } 

} 

func pauseLayer(layer : CALayer){ 
    let pausedTime : CFTimeInterval = layer.convertTime(CACurrentMediaTime(), fromLayer: nil) 
    layer.speed = 0.0 
    layer.timeOffset = pausedTime 

} 



override func didReceiveMemoryWarning(){ 
    super.didReceiveMemoryWarning() 
    // Dispose of any resources that can be recreated. 
} 
override func viewDidLoad() { 
    super.viewDidLoad() 
    // Do any additional setup after loading the view, typically from a nib. 
    setUpView() 

} 

我遇到的問題是變量「層」只能暫停（當通過「pauseLayer」函數傳遞時），如果它是全局變量！我不知道爲什麼！我想在「handleLongPress」函數中聲明變量。原因是因爲我需要在每次識別longPressGestureRecognizer時聲明一個具有相同名稱的新變量。我曾嘗試通過引用與「inout」，但它似乎沒有工作。有人可以幫忙嗎？請。

Answer 1

使用此修改後的代碼：

//Global Variables 
var layer: CALayer? 
var holdGesture = UILongPressGestureRecognizer() 
let animation = CABasicAnimation(keyPath: "bounds.size.width") 


func setUpView(){ 

    self.view.addGestureRecognizer(holdGesture) 
    holdGesture.addTarget(self, action:"handleLongPress:") 

} 


func handleLongPress(sender : UILongPressGestureRecognizer){ 

    if(sender.state == .Began) { 

     let newLayer = CALayer() 
     newLayer.frame = CGRect(x: 0, y: 0, width: 0, height: 10) 
     newLayer.backgroundColor = UIColor.redColor().CGColor 

     animation.fromValue = 0 
     animation.toValue = self.view.bounds.width * 2 
     animation.duration = 5 
     self.view.layer.addSublayer(newLayer) 

     print("Long Press Began") 
     newLayer.addAnimation(animation, forKey: "bounds.size.width") 

     layer = newLayer 
    } 
    else { 
     print("Long press ended") 

     if let layer = layer { 
      pauseLayer(layer) 
      layer.removeFromSuperlayer() 
     } 
    } 

} 

func pauseLayer(layer : CALayer){ 
    let pausedTime : CFTimeInterval = layer.convertTime(CACurrentMediaTime(), fromLayer: nil) 
    layer.speed = 0.0 
    layer.timeOffset = pausedTime 

}