如何在 Swift 中持续创建涟漪效果并在延迟一段时间后重复该过程

Question

我正在开发一个 iOS 应用程序，我需要在 UIView 上创建涟漪效果。我可以创建涟漪效果，但无法自定义。这就是我想要实现的目标：

这是我当前的输出

我想要实现的是连续创建 4-5 个涟漪，然后在一些延迟之后再产生 4-5 个涟漪并无限重复该过程。但目前我只能产生 1 个波纹（它会无限传播）。

这是我的代码：

func addRipple(rView: UIView) {
    let path = UIBezierPath(ovalIn: CGRect(x: 0, y: 0, width: rView.bounds.size.width, height: rView.bounds.size.height))

    let shapePosition = CGPoint(x: rView.bounds.size.width / 2.0, y: rView.bounds.size.height / 2.0)
    let rippleShape = CAShapeLayer()
    rippleShape.bounds = CGRect(x: 0, y: 0, width: rView.bounds.size.width, height: rView.bounds.size.height)
    rippleShape.path = path.cgPath
    rippleShape.fillColor = UIColor.clear.cgColor
    rippleShape.strokeColor = UIColor.systemBlue.cgColor
    rippleShape.lineWidth = 1
    rippleShape.position = shapePosition
    rippleShape.opacity = 0
    
    rView.layer.addSublayer(rippleShape)

    let scaleAnim = CABasicAnimation(keyPath: "transform.scale")
    scaleAnim.fromValue = NSValue(caTransform3D: CATransform3DIdentity)
    scaleAnim.toValue = NSValue(caTransform3D: CATransform3DMakeScale(2, 2, 1))

    let opacityAnim = CABasicAnimation(keyPath: "opacity")
    opacityAnim.fromValue = 1
    opacityAnim.toValue = nil

    let animation = CAAnimationGroup()
    animation.animations = [scaleAnim, opacityAnim]
    animation.timingFunction = CAMediaTimingFunction(name: CAMediaTimingFunctionName.easeOut)
    animation.duration = 1
    animation.repeatCount = Float.infinity
    animation.isRemovedOnCompletion = false
    rippleShape.add(animation, forKey: "rippleEffect")
}

这就是我调用 addRipple 方法的方式

@IBOutlet weak var sView: UIView!
override func viewDidLoad() {
    super.viewDidLoad()
    sView.layer.cornerRadius = sView.frame.size.width / 2
    sView.layer.borderWidth = 2
    sView.layer.borderColor = UIColor.systemBlue.cgColor
    addRipple(to: sView)
}

我觉得我很接近，但我无法弄清楚。

提前致谢。

Answer 1

你可以使用这个 Pod 或 UIView Extension

信用：https://github.com/janlionly/UIView-Ripple/blob/master/Source/UIView%2BRipple.swift

Answer 2

如果我没理解错的话，你希望这些涟漪中的多个同时出现在屏幕上。在这种情况下，如果您创建多个圆形子图层并使用不同的

timeOffset

为它们中的每一个设置动画，将会更方便。

let path = UIBezierPath(ovalIn: CGRect(x: 0, y: 0, width: rView.bounds.size.width, height: rView.bounds.size.height))
let shapePosition = CGPoint(x: rView.bounds.size.width / 2.0, y: rView.bounds.size.height / 2.0)

for i in 0..<4 {
    let rippleShape = CAShapeLayer()
    
    // set up rippleShape as usual here...
    
    rView.layer.addSublayer(rippleShape)
    
    // set these up as usual too...
    let scaleAnim = ...
    let opacityAnim = ...

    let animation = CAAnimationGroup()
    animation.animations = [scaleAnim, opacityAnim]
    animation.timingFunction = CAMediaTimingFunction(name: CAMediaTimingFunctionName.easeOut)
    animation.repeatCount = Float.infinity
    animation.duration = 2
    animation.isRemovedOnCompletion = false

    // this is the important section
    // let timeInBetweenRipples = 0.2
    animation.timeOffset = timeInBetweenRipples * Double(i)
    animation.speed = 0.5
    // You can tweak speed, timeInBetweenRipples, and duration as you see fit

    // don't forget to give each animation a different key
    rippleShape.add(animation, forKey: "rippleEffect\(i)")
}

动画的一帧是这样的：