ios - 动画 CALayer 边框 alpha

Question

我有一个带边框的 UIView(颜色:绿色，宽度:10)。

我正在尝试将边框的 alpha(在循环中)从 1.0 的值设置为 0.2 的值 - 然后回到 1.0 - 然后回到 0.2 等...

但是 CALayer 没有 borderAlpha 的属性，所以我不确定我该怎么做。

我试过这段代码，但没有成功:

UIView.animate(withDuration: 1, delay: 0, options: [.repeat, .autoreverse], animations: {
    self.layer.borderColor = UIColor(cgColor: self.layer.borderColor!).withAlphaComponent(0.2).cgColor
}, completion: nil)

有人知道我该怎么做吗？

谢谢!

Answer 1

尝试使用这个

class animateStack: UIViewController {

    @IBOutlet weak var animateView: UIView!{
        didSet{
            animateView.layer.borderColor = UIColor.black.cgColor
            animateView.layer.borderWidth = 10
        }
    }

    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view.
        animateBorderAlpha()
    }

    private func animateBorderAlpha(){
        /// First Animation
        let animation = CABasicAnimation(keyPath: "borderColor")
        animation.beginTime = 0
        animation.toValue = UIColor.black.withAlphaComponent(0.1).cgColor
        animation.fromValue = UIColor.black.cgColor
        animation.duration = 2

        /// Second Animation
        let animation1 = CABasicAnimation(keyPath: "borderColor")
        animation1.toValue = UIColor.black.cgColor
        animation1.fromValue = UIColor.black.withAlphaComponent(0.1).cgColor
        animation1.beginTime = animation.beginTime + animation.duration
        animation.duration = 4

        /// Animation Group
        let borderColorAnimation: CAAnimationGroup = CAAnimationGroup()
        borderColorAnimation.animations = [animation, animation1]
        borderColorAnimation.duration = animation.duration + animation1.duration
        borderColorAnimation.repeatCount = Float.greatestFiniteMagnitude
        self.animateView.layer.add(borderColorAnimation, forKey: "borderColor")
    }

}

更新

class animateViewClass: NSObject {
    class func animateBorderAlpha(_ view: UIView){
        /// First Animation
        let animation = CABasicAnimation(keyPath: "borderColor")
        animation.beginTime = 0
        animation.toValue = UIColor.black.withAlphaComponent(0.1).cgColor
        animation.fromValue = UIColor.black.cgColor
        animation.duration = 2

        /// Second Animation
        let animation1 = CABasicAnimation(keyPath: "borderColor")
        animation1.toValue = UIColor.black.cgColor
        animation1.fromValue = UIColor.black.withAlphaComponent(0.1).cgColor
        animation1.beginTime = animation.beginTime + animation.duration
        animation.duration = 4

        /// Animation Group
        let borderColorAnimation: CAAnimationGroup = CAAnimationGroup()
        borderColorAnimation.animations = [animation, animation1]
        borderColorAnimation.duration = animation.duration + animation1.duration
        borderColorAnimation.repeatCount = Float.greatestFiniteMagnitude
        view.layer.add(borderColorAnimation, forKey: "borderColor")
    }
}

用法

    animateViewClass.animateBorderAlpha(viewName)
    /// Case of Subclass UIView
    animateViewClass.animateBorderAlpha(self)