永远不会调用 CAAnimationDelegate 委托

Question

我用两个 CAShapeLayer's 做了一个简单的进度线。动画工作正常，但从未调用 CAAnimationDelegate animationDidStart 和 animationDidStop。

这是我的代码：

class ProgressBar: UIView, CAAnimationDelegate {

    var bottomProgressBar = CAShapeLayer()
    var topProgressBar = CAShapeLayer()
    let animation = CABasicAnimation(keyPath: "strokeEnd")

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

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

    func configure() {
        animation.delegate = self

        // setup the two layers
    }

    func animate(toValue: Double) {

        animation.duration = 1.0
        animation.fromValue = 0
        animation.toValue = toValue

        topProgressBar.strokeEnd = CGFloat(toValue)
        topProgressBar.animation(forKey: "animate")
    }

    func animationDidStart(_ anim: CAAnimation) {
        print("start")
    }

    func animationDidStop(_ anim: CAAnimation, finished flag: Bool) {
        print("stop")
    }
}

animate 方法被多次调用，取值范围为 0 到 1。

有谁知道为什么从未调用这些代表？

Answer 1

编辑：在下面的每个评论中添加带有链接的正确解决方案

您正在调用 topProgressBar。animation(forKey: "animate") which actually returns the animation; it doesn't start it. You should call layer.add(animation, forKey:) 而不是

永远不会调用 CAAnimationDelegate 委托

CAAnimationDelegate delegates are never called

cabasicanimation

ios

swift