ビューのアニメーションが背景に移動した後に動作しない（swift 3）

Question

私は現在、スウィフト3でカウントダウンアプリを開発中です。 カウンタの後ろに、カウンタに従ってアニメーションされた円が作成されました。 私の問題は簡単です。私は家に居るときにアプリをバックグラウンドに置くと、アプリに戻ってももうアニメーションが動かなくなります。 私は理由を知らない。興味深い事実： "描画"は無地の円であり、境界線のみがアニメーション化されています。サークルの背景はまだOKです。それはもはや動作していないボーダーアニメーションだけです。ここで

私のコードです：

override func viewDidAppear(_ animated: Bool) { 
     super.viewDidAppear(animated) 
     let screen = self.view.frame.size.width 
     let y = CGFloat(190) 
     let circleWidth = CGFloat(200) 
     let circleHeight = circleWidth 

     // Create a new CircleView 
     let circleView = CircleView(frame: CGRect(x: (screen/2) - (circleWidth/2), y: y, width: circleWidth, height: circleHeight)) 

     view.addSubview(circleView) 

     // Animate the drawing of the circle over the course of 1 second 
     circleView.animateCircle(TimeInterval(seconds)) 
    } 

CircleViewクラス：

import Foundation 
import UIKit 

class CircleView: UIView{ 
    var circleLayer: CAShapeLayer! 

    override init(frame: CGRect) { 
     super.init(frame: frame) 
     self.backgroundColor = UIColor.clear 

     // Use UIBezierPath as an easy way to create the CGPath for the layer. 
     // The path should be the entire circle. 
     let circlePath = UIBezierPath(arcCenter: CGPoint(x: frame.size.width/2.0, y: frame.size.height/2.0), radius: (frame.size.width - 10)/2, startAngle: CGFloat(-M_PI/2), endAngle: CGFloat(M_PI*1.5), clockwise: true) 

     // Setup the CAShapeLayer with the path, colors, and line width 
     circleLayer = CAShapeLayer() 
     circleLayer.path = circlePath.cgPath 
     circleLayer.fillColor = UIColor(red: 255/255, green: 255/255, blue: 255/255, alpha: 0.2).cgColor 
     circleLayer.strokeColor = UIColor(red: 165/255, green: 219/255, blue: 255/255, alpha: 0.8).cgColor 
     circleLayer.lineWidth = 2.0; 

     // Don't draw the circle initially 
     circleLayer.strokeEnd = 0.0 

     // Add the circleLayer to the view's layer's sublayers 
     layer.addSublayer(circleLayer) 
    } 

    required init?(coder aDecoder: NSCoder) { 
     fatalError("init(coder:) has not been implemented") 
    } 


    func animateCircle(_ duration: TimeInterval) { 
     // We want to animate the strokeEnd property of the circleLayer 
     let animation = CABasicAnimation(keyPath: "strokeEnd") 

     // Set the animation duration appropriately 
     animation.duration = duration 

     // Animate from 0 (no circle) to 1 (full circle) 
     animation.fromValue = 1 
     animation.toValue = 0 

     // Do a linear animation (i.e. the speed of the animation stays the same) 
     animation.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionLinear) 

     // Set the circleLayer's strokeEnd property to 1.0 now so that it's the 
     // right value when the animation ends. 
     circleLayer.strokeEnd = 0.0 

     // Do the actual animation 
     circleLayer.add(animation, forKey: "animateCircle") 
    } 

} 

は、あなたが答え:)

Answer 1

を持っている場合あなたがする必要があるのは、1以上を追加で事前にありがとうアニメーションコードの行：

animation.isRemovedOnCompletion = false 

となり、コードは

func animateCircle(_ duration: TimeInterval) { 
    // We want to animate the strokeEnd property of the circleLayer 
    let animation = CABasicAnimation(keyPath: "strokeEnd") 

    // Set the animation duration appropriately 
    animation.duration = duration 

    // Animate from 0 (no circle) to 1 (full circle) 
    animation.fromValue = 1 
    animation.toValue = 0 

    // Do a linear animation (i.e. the speed of the animation stays the same) 
    animation.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionLinear) 

    animation.isRemovedOnCompletion = false 

    // Set the circleLayer's strokeEnd property to 1.0 now so that it's the 
    // right value when the animation ends. 
    circleLayer.strokeEnd = 0.0 

    // Do the actual animation 
    circleLayer.add(animation, forKey: "animateCircle") 
}