Ios 使用CAShapeLayer对圆进行多次动画制作

当用户点击一个按钮时，我需要设置一个圆圈的进度动画。我目前正在使用

CAShapeLayer

和

CABasicAnimation

。代码如下：

import UIKit

class ViewController: UIViewController {


    @IBOutlet weak var circleContainerView: UIView!

    var progressPts = [0.1, 0.3, 0.7, 0.5]
    let circleLayer = CAShapeLayer()

    override func viewDidLoad() {
        super.viewDidLoad()
        setupCircle()
    }

    @IBAction func didTapAnimate(_ sender: Any) {
        guard let pt = progressPts.first else { return }
        let animateStroke = CABasicAnimation(keyPath: "strokeEnd")
        animateStroke.toValue = pt
        animateStroke.duration = 2.0
        animateStroke.fillMode = .forwards
        animateStroke.isRemovedOnCompletion = false
        circleLayer.add(animateStroke, forKey: "MyAnimation")
        progressPts.removeFirst()
    }

    private func setupCircle() {
        circleLayer.frame = CGRect(origin: .zero, size: circleContainerView.bounds.size)
        let center = CGPoint(x: circleLayer.bounds.width / 2.0,
                             y: circleLayer.bounds.height / 2.0)
        circleLayer.path = UIBezierPath(arcCenter: center,
                                        radius: (circleLayer.bounds.height / 2.0) - 5.0,
                                        startAngle: 0,
                                        endAngle: 2 * CGFloat.pi, clockwise: true).cgPath
        circleLayer.fillColor = UIColor.clear.cgColor
        circleLayer.lineWidth = 10.0
        circleLayer.strokeColor = UIColor.red.cgColor
        circleLayer.strokeEnd = 0.0
        circleContainerView.layer.addSublayer(circleLayer)
    }

}

为了在动画结束时笔划保持在正确的位置，我需要将

填充模式
也设置为
。向前
和
isRemovedOnCompletion
设置为
false
。这适用于第一个动画。但是，在下一个动画中，斯托克首先重置：


我做错了什么？如何在不重置的情况下为每个新的进度位置设置动画？另外，将
isRemovedOnCompletion
设置为
false
当然是一个坏主意，因为该层最终将附加多个动画。
我刚刚使用了“从值”属性来完成循环，而没有重置，它将平滑地设置动画，只需使用下面的代码即可

import UIKit

class ViewController: UIViewController {

    @IBOutlet weak var circleContainerView: UIView!
    var progressPts = [0.1, 0.3, 0.7, 0.5]
    var previousPts = 0.0
    let circleLayer = CAShapeLayer()
    var animateStroke: CABasicAnimation! 
    override func viewDidLoad() {
            super.viewDidLoad()
            setupCircle()
        }

        @IBAction func didTapAnimate(_ sender: Any) {
            guard let pt = progressPts.first else { return }
            animateStroke.fromValue = previousPts
            animateStroke.toValue = pt
            animateStroke.duration = 2.0
            animateStroke.fillMode = .forwards
            animateStroke.isRemovedOnCompletion = false
            circleLayer.add(animateStroke, forKey: "MyAnimation")
            previousPts = progressPts.removeFirst()
        }

        private func setupCircle() {
             animateStroke =  CABasicAnimation(keyPath: "strokeEnd")
            circleLayer.frame = CGRect(origin: .zero, size: circleContainerView.bounds.size)
            let center = CGPoint(x: circleLayer.bounds.width / 2.0,
                                 y: circleLayer.bounds.height / 2.0)
            circleLayer.path = UIBezierPath(arcCenter: center,
                                            radius: (circleLayer.bounds.height / 2.0) - 5.0,
                                            startAngle: 0,
                                            endAngle: 2 * CGFloat.pi, clockwise: true).cgPath
            circleLayer.fillColor = UIColor.clear.cgColor
            circleLayer.lineWidth = 10.0
            circleLayer.strokeColor = UIColor.red.cgColor
            circleLayer.strokeEnd = 0.0
            circleContainerView.layer.addSublayer(circleLayer)
        }

    }

输出

希望以下解决方案对您有效。您应用了以下解决方案吗？谢谢。我忘了从value更改
。但是，使用此解决方案，每次都会向层添加一个新动画。因为
isRemovedOnCompletion
设置为
false
。这不会对性能产生负面影响吗？您可以通过在setupCircle方法内部初始化
animateStroke
来优化代码，这样它将只初始化一次，并且只更新值（请参阅更新的代码）。我认为这不会影响性能。