如何将带有参数的CAshapelayer添加到子层

Question

NewBie！

我有一个缩放/脉冲动画，如下所示在for循环中的cgPaths上工作。该代码有效，但仅当将circleLayer已添加到animatedLayers并将circleLayer附加到subLayer路径并且在动画（DispatchQueue）开始之前创建一个静态圆（类似毛刺）时，此代码才有效。 。

...
self.layer.addSublayer(animatedLayer)
animatedLayers.append(animatedLayer)
...

是否可以将带有参数的CAShapeLayer添加到subLayer？如果不是，是否有建议的替代方法？

import UIKit
import Foundation

@IBDesignable
class AnimatedCircleView: UIView {

    // MARK: - Initializers

    var animatedLayers = [CAShapeLayer]()

    // MARK: - Methods

    override func draw(_ rect: CGRect) {

        // Animated circle
        for _ in 0...3 {
            let animatedPath = UIBezierPath(arcCenter: .zero, radius: self.layer.bounds.size.width / 2.3,
            startAngle: 0, endAngle: 2 * CGFloat.pi, clockwise: true)
            let animatedLayer = CAShapeLayer()

            animatedLayer.path = animatedPath.cgPath
            animatedLayer.strokeColor = UIColor.black.cgColor
            animatedLayer.lineWidth = 0
            animatedLayer.fillColor = UIColor.gray.cgColor
            animatedLayer.lineCap = CAShapeLayerLineCap.round
            animatedLayer.position = CGPoint(x: self.layer.bounds.size.width / 2, y: self.layer.bounds.size.width / 2)
            self.layer.addSublayer(animatedLayer)
            animatedLayers.append(animatedLayer)
        }

        // Dispatch animation for circle _ 0...3
        DispatchQueue.main.asyncAfter(deadline: .now() + 0.1) {
            self.animateCircle(index: 0)
            DispatchQueue.main.asyncAfter(deadline: .now() + 0.2) {
                self.animateCircle(index: 1)
                DispatchQueue.main.asyncAfter(deadline: .now() + 0.3) {
                    self.animateCircle(index: 2)
                    DispatchQueue.main.asyncAfter(deadline: .now() + 0.4) {
                        self.animateCircle(index: 3)
                    }
                }
            }
        }
    }


    func animateCircle(index: Int) {

        let scaleAnimation = CABasicAnimation(keyPath: "transform.scale")
        scaleAnimation.duration = 1.8
        scaleAnimation.fromValue = 0
        scaleAnimation.toValue = 1
        scaleAnimation.timingFunction = CAMediaTimingFunction(name: CAMediaTimingFunctionName.easeOut)
        scaleAnimation.repeatCount = Float.infinity
        animatedLayers[index].add(scaleAnimation, forKey: "scale")

        let opacityAnimation = CABasicAnimation(keyPath: #keyPath(CALayer.opacity))
        opacityAnimation.duration = 1.8
        opacityAnimation.fromValue = 0.7
        opacityAnimation.toValue = 0
        opacityAnimation.timingFunction = CAMediaTimingFunction(name: CAMediaTimingFunctionName.easeOut)
        opacityAnimation.repeatCount = Float.infinity
        animatedLayers[index].add(opacityAnimation, forKey: "opacity")
    }
}

Answer 1

您是否尝试以填充色开始清晰，然后在动画开始时将其变成灰色？

    // Animated circle
    for _ in 0...3 {
        let animatedPath = UIBezierPath(arcCenter: .zero, radius: self.layer.bounds.size.width / 2.3,
        startAngle: 0, endAngle: 2 * CGFloat.pi, clockwise: true)
        let animatedLayer = CAShapeLayer()

        animatedLayer.path = animatedPath.cgPath
        animatedLayer.strokeColor = UIColor.black.cgColor
        animatedLayer.lineWidth = 0
        animatedLayer.fillColor = UIColor.clear.cgColor
        animatedLayer.lineCap = CAShapeLayerLineCap.round
        animatedLayer.position = CGPoint(x: self.layer.bounds.size.width / 2, y: self.layer.bounds.size.width / 2)
        self.layer.addSublayer(animatedLayer)
        animatedLayers.append(animatedLayer)
    }

    // Dispatch animation for circle _ 0...3
    DispatchQueue.main.asyncAfter(deadline: .now() + 0.1) {

        self.animateCircle(index: 0)
        animatedLayer.fillColor = UIColor.grey.cgColor
        DispatchQueue.main.asyncAfter(deadline: .now() + 0.2) {
            self.animateCircle(index: 1)
            DispatchQueue.main.asyncAfter(deadline: .now() + 0.3) {
                self.animateCircle(index: 2)
                DispatchQueue.main.asyncAfter(deadline: .now() + 0.4) {
                    self.animateCircle(index: 3)
                }
            }
        }
    }
}