swift - CABasicAnimation 开始时的故障

问题描述

我有一个缩放/脉冲动画，它在 for 循环中处理 cgPaths，如下所示。此代码有效，但仅当您已将附加animatedLayers到circleLayer路径时才有效，并且这会在动画 ( ) 开始之前创建一个静态圆圈（类似故障）...circleLayersubLayerDispatchQueue

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

是否可以将CAShapeLayer带参数添加到子层？如果没有，有什么推荐的替代品吗？

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")
    }
}

标签： swiftcashapelayercabasicanimation

解决方案

关键问题是您的动画开始时有交错的延迟，在 0.1 到 1.0 秒之间。在最后一个动画开始之前，该层只是坐在那里，全尺寸和 100% 不透明度。

由于您正在将变换比例从 0 设置为 1，因此我建议将起始变换设置为 0（或将更改opacity为 0）。然后你不会看到他们坐在那里，直到他们各自的动画开始。

其他一些观察：

这draw(_:)不是添加图层、启动动画等的正确位置。此方法可能会被多次调用，并且应该代表给定时间点的视图。我会退休draw(_:)，因为它不是开始这个的正确地方，你根本不需要这种方法。
您在 0.1 秒后开始您的第一个动画。为什么不立即启动呢？
path您应该通过将和position属性的设置推迟到来处理框架调整layoutSubviews。

因此：

@IBDesignable
class AnimatedCircleView: UIView {
    private var animatedLayers = [CAShapeLayer]()

    override init(frame: CGRect = .zero) {
        super.init(frame: frame)
        configure()
    }

    required init?(coder: NSCoder) {
        super.init(coder: coder)
        configure()
    }

    override func layoutSubviews() {
        super.layoutSubviews()

        let path = UIBezierPath(arcCenter: .zero, radius: bounds.width / 2.3, startAngle: 0, endAngle: 2 * .pi, clockwise: true)

        for animatedLayer in animatedLayers {
            animatedLayer.path = path.cgPath
            animatedLayer.position = CGPoint(x: bounds.midX, y: bounds.midY)
        }
    }
}

// MARK: - Methods

private extension AnimatedCircleView {
    func configure() {
        for _ in 0...3 {
            let animatedLayer = CAShapeLayer()
            animatedLayer.strokeColor = UIColor.black.cgColor
            animatedLayer.lineWidth = 0
            animatedLayer.fillColor = UIColor.gray.cgColor
            animatedLayer.lineCap = .round
            animatedLayer.transform = CATransform3DMakeScale(0, 0, 1)
            layer.addSublayer(animatedLayer)
            animatedLayers.append(animatedLayer)
        }

        self.animateCircle(index: 0)
        DispatchQueue.main.asyncAfter(deadline: .now() + 0.1) {
            self.animateCircle(index: 1)
            DispatchQueue.main.asyncAfter(deadline: .now() + 0.2) {
                self.animateCircle(index: 2)
                DispatchQueue.main.asyncAfter(deadline: .now() + 0.3) {
                    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 = .greatestFiniteMagnitude
        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 = .greatestFiniteMagnitude
        animatedLayers[index].add(opacityAnimation, forKey: "opacity")
    }
}

swift - CABasicAnimation 开始时的故障

问题描述

解决方案

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