动画绘制圆圈

时间：2014-10-26 21:13:48

标签： swift geometry uiviewanimation progress drawrect

我正在寻找一种动画绘制圆圈的方法。我已经能够创建圆圈，但它将所有这些组合在一起。

这是我的CircleView课程：

import UIKit

class CircleView: UIView {
  override init(frame: CGRect) {
    super.init(frame: frame)
    self.backgroundColor = UIColor.clearColor()
  }

  required init(coder aDecoder: NSCoder) {
    fatalError("init(coder:) has not been implemented")
  }


  override func drawRect(rect: CGRect) {
    // Get the Graphics Context
    var context = UIGraphicsGetCurrentContext();

    // Set the circle outerline-width
    CGContextSetLineWidth(context, 5.0);

    // Set the circle outerline-colour
    UIColor.redColor().set()

    // Create Circle
    CGContextAddArc(context, (frame.size.width)/2, frame.size.height/2, (frame.size.width - 10)/2, 0.0, CGFloat(M_PI * 2.0), 1)

    // Draw
    CGContextStrokePath(context);
  }
}

以下是我如何将其添加到视图控制器中的视图层次结构中：

func addCircleView() {
    let diceRoll = CGFloat(Int(arc4random_uniform(7))*50)
    var circleWidth = CGFloat(200)
    var circleHeight = circleWidth
    // Create a new CircleView
    var circleView = CircleView(frame: CGRectMake(diceRoll, 0, circleWidth, circleHeight))

    view.addSubview(circleView)
}

有没有办法在1秒内为圆形绘制设置动画？

示例，在动画的某个部分，它看起来像这个图像中的蓝线：

partial animation

6 个答案:

答案 0 :(得分：185)

最简单的方法是使用核心动画的强大功能为您完成大部分工作。为此，我们必须将您的圈子绘图代码从drawRect函数移动到CAShapeLayer。然后，我们可以使用CABasicAnimation为CAShapeLayer 0.0 1.0 strokeEnd的{​​{1}}属性设置动画。 strokeEnd是这里神奇的重要组成部分;来自文档：

  

结合strokeStart属性，此属性定义了   中风路径的次区域。此属性中的值表示   沿着路径完成抚摸的相对点   strokeStart属性定义起点。值0.0   表示路径的开头，而值1.0表示   路径的尽头。中间的值沿线性解释   路径长度。

如果我们将0.0设置为1.0，则无法绘制任何内容。如果我们将其设置为0.5，则会绘制一个完整的圆圈。如果我们将其设置为CAShapeLayer，则会绘制半个圆圈。等

首先，让我们在CircleView init函数中创建sublayers，然后将该图层添加到视图drawRect （同样一定要删除let circleLayer: CAShapeLayer! override init(frame: CGRect) { super.init(frame: frame) self.backgroundColor = UIColor.clearColor() // Use UIBezierPath as an easy way to create the CGPath for the layer. // The path should be the entire circle. let circlePath = UIBezierPath(arcCenter: CGPoint(x: frame.size.width / 2.0, y: frame.size.height / 2.0), radius: (frame.size.width - 10)/2, startAngle: 0.0, endAngle: CGFloat(M_PI * 2.0), clockwise: true) // Setup the CAShapeLayer with the path, colors, and line width circleLayer = CAShapeLayer() circleLayer.path = circlePath.CGPath circleLayer.fillColor = UIColor.clearColor().CGColor circleLayer.strokeColor = UIColor.redColor().CGColor circleLayer.lineWidth = 5.0; // Don't draw the circle initially circleLayer.strokeEnd = 0.0 // Add the circleLayer to the view's layer's sublayers layer.addSublayer(circleLayer) } 函数，因为图层现在将绘制圆圈：

circleLayer.strokeEnd = 0.0

注意：我们正在设置func animateCircle(duration: NSTimeInterval) { // We want to animate the strokeEnd property of the circleLayer let animation = CABasicAnimation(keyPath: "strokeEnd") // Set the animation duration appropriately animation.duration = duration // Animate from 0 (no circle) to 1 (full circle) animation.fromValue = 0 animation.toValue = 1 // Do a linear animation (i.e. the speed of the animation stays the same) animation.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionLinear) // Set the circleLayer's strokeEnd property to 1.0 now so that it's the // right value when the animation ends. circleLayer.strokeEnd = 1.0 // Do the actual animation circleLayer.addAnimation(animation, forKey: "animateCircle") } ，以便不立即绘制圆圈。

现在，让我们添加一个我们可以调用的函数来触发圆形动画：

addCircleView

然后，我们需要做的就是更改您的CircleView功能，以便在superview添加func addCircleView() { let diceRoll = CGFloat(Int(arc4random_uniform(7))*50) var circleWidth = CGFloat(200) var circleHeight = circleWidth // Create a new CircleView var circleView = CircleView(frame: CGRectMake(diceRoll, 0, circleWidth, circleHeight)) view.addSubview(circleView) // Animate the drawing of the circle over the course of 1 second circleView.animateCircle(1.0) } 时触发动画：

{{1}}

所有这些看起来应该是这样的：

circle animation

注意：它不会像这样重复，它会在动画后保持整整一圈。

答案 1 :(得分：22)

为Swift 3.0更新了Mikes答案

var circleLayer: CAShapeLayer!

override init(frame: CGRect) {
    super.init(frame: frame)
    self.backgroundColor = UIColor.clear

    // Use UIBezierPath as an easy way to create the CGPath for the layer.
    // The path should be the entire circle.
    let circlePath = UIBezierPath(arcCenter: CGPoint(x: frame.size.width / 2.0, y: frame.size.height / 2.0), radius: (frame.size.width - 10)/2, startAngle: 0.0, endAngle: CGFloat(M_PI * 2.0), clockwise: true)

    // Setup the CAShapeLayer with the path, colors, and line width
    circleLayer = CAShapeLayer()
    circleLayer.path = circlePath.cgPath
    circleLayer.fillColor = UIColor.clear.cgColor
    circleLayer.strokeColor = UIColor.red.cgColor
    circleLayer.lineWidth = 5.0;

    // Don't draw the circle initially
    circleLayer.strokeEnd = 0.0

    // Add the circleLayer to the view's layer's sublayers
    layer.addSublayer(circleLayer)
} 

required init?(coder aDecoder: NSCoder) {
        fatalError("init(coder:) has not been implemented")
}

func animateCircle(duration: TimeInterval) {
    // We want to animate the strokeEnd property of the circleLayer
    let animation = CABasicAnimation(keyPath: "strokeEnd")

    // Set the animation duration appropriately
    animation.duration = duration

    // Animate from 0 (no circle) to 1 (full circle)
    animation.fromValue = 0
    animation.toValue = 1

    // Do a linear animation (i.e The speed of the animation stays the same)
    animation.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionLinear)

    // Set the circleLayer's strokeEnd property to 1.0 now so that it's the
    // Right value when the animation ends
    circleLayer.strokeEnd = 1.0

    // Do the actual animation
    circleLayer.add(animation, forKey: "animateCircle")
}

调用该函数：

func addCircleView() {
    let diceRoll = CGFloat(Int(arc4random_uniform(7))*50)
    var circleWidth = CGFloat(200)
    var circleHeight = circleWidth

    // Create a new CircleView
    let circleView = CircleView(frame: CGRect(x: diceRoll, y: 0, width: circleWidth, height: circleHeight))
    //let test = CircleView(frame: CGRect(x: diceRoll, y: 0, width: circleWidth, height: circleHeight))

    view.addSubview(circleView)

    // Animate the drawing of the circle over the course of 1 second
    circleView.animateCircle(duration: 1.0)
}

答案 2 :(得分：15)

迈克的答案很棒！另一个很好而简单的方法是使用drawRect和setNeedsDisplay（）。看起来很迟钝，但不是:-) enter image description here

我们想从顶部开始绘制一个圆圈，即-90°并以270°结束。圆的中心是（centerX，centerY），具有给定的半径。 CurrentAngle是圆的终点的当前角度，从minAngle（-90）到maxAngle（270）。

// MARK: Properties
let centerX:CGFloat = 55
let centerY:CGFloat = 55
let radius:CGFloat = 50

var currentAngle:Float = -90
let minAngle:Float = -90
let maxAngle:Float = 270

在drawRect中，我们指定圆圈应该如何显示：

override func drawRect(rect: CGRect) {

    let context = UIGraphicsGetCurrentContext()

    let path = CGPathCreateMutable()

    CGPathAddArc(path, nil, centerX, centerY, radius, CGFloat(GLKMathDegreesToRadians(minAngle)), CGFloat(GLKMathDegreesToRadians(currentAngle)), false)

    CGContextAddPath(context, path)
    CGContextSetStrokeColorWithColor(context, UIColor.blueColor().CGColor)
    CGContextSetLineWidth(context, 3)
    CGContextStrokePath(context)
}

现在的问题是，由于currentAngle没有改变，因此圆圈是静态的，甚至不显示，因为currentAngle = minAngle。

然后我们创建一个计时器，每当该计时器触发时，我们都会增加currentAngle。在班级的顶部，添加两次火灾之间的时间安排：

let timeBetweenDraw:CFTimeInterval = 0.01

在你的init中，添加计时器：

NSTimer.scheduledTimerWithTimeInterval(timeBetweenDraw, target: self, selector: #selector(updateTimer), userInfo: nil, repeats: true)

我们可以添加定时器触发时调用的函数：

func updateTimer() {

    if currentAngle < maxAngle {
        currentAngle += 1
    }
}

可悲的是，在运行应用程序时，没有任何内容显示，因为我们没有指定它应该再次绘制的系统。这是通过调用setNeedsDisplay（）来完成的。这是更新的计时器功能：

func updateTimer() {

    if currentAngle < maxAngle {
        currentAngle += 1
        setNeedsDisplay()
    }
}

_ _ _

您需要的所有代码总结如下：

import UIKit
import GLKit

class CircleClosing: UIView {

    // MARK: Properties
    let centerX:CGFloat = 55
    let centerY:CGFloat = 55
    let radius:CGFloat = 50

    var currentAngle:Float = -90

    let timeBetweenDraw:CFTimeInterval = 0.01

    // MARK: Init
    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        setup()
    }

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

    func setup() {
        self.backgroundColor = UIColor.clearColor()
        NSTimer.scheduledTimerWithTimeInterval(timeBetweenDraw, target: self, selector: #selector(updateTimer), userInfo: nil, repeats: true)
    }

    // MARK: Drawing
    func updateTimer() {

        if currentAngle < 270 {
            currentAngle += 1
            setNeedsDisplay()
        }
    }

    override func drawRect(rect: CGRect) {

        let context = UIGraphicsGetCurrentContext()

        let path = CGPathCreateMutable()

        CGPathAddArc(path, nil, centerX, centerY, radius, -CGFloat(M_PI/2), CGFloat(GLKMathDegreesToRadians(currentAngle)), false)

        CGContextAddPath(context, path)
        CGContextSetStrokeColorWithColor(context, UIColor.blueColor().CGColor)
        CGContextSetLineWidth(context, 3)
        CGContextStrokePath(context)
    }
}

如果要更改速度，只需修改updateTimer函数或调用此函数的速率。此外，您可能希望在圆圈完成后使计时器无效，我忘了这样做： - ）

注意：要在故事板中添加圈子，只需添加视图，选择它，转到 Identity Inspector ，然后选择 Class ，指定 CircleClosing

干杯！ BRO

答案 3 :(得分：11)

如果你想要一个完成处理程序，这是另一个类似于Mike S的解决方案，在Swift 3.0中完成

func animateCircleFull(duration: TimeInterval) {
    CATransaction.begin()
    let animation = CABasicAnimation(keyPath: "strokeEnd")
    animation.duration = duration
    animation.fromValue = 0
    animation.toValue = 1
    animation.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseInEaseOut)
    circleLayer.strokeEnd = 1.0
    CATransaction.setCompletionBlock {
        print("animation complete")
    }
    // Do the actual animation
    circleLayer.add(animation, forKey: "animateCircle")
    CATransaction.commit()
}

使用完成处理程序，您可以通过递归调用相同的函数再次运行动画（这看起来非常好），或者您可以使用反向函数来连续链接直到满足条件，例如：

func animate(duration: TimeInterval){
    self.isAnimating = true
    self.animateCircleFull(duration: 1)
}

func endAnimate(){
    self.isAnimating = false
}

func animateCircleFull(duration: TimeInterval) {
    if self.isAnimating{
        CATransaction.begin()
        let animation = CABasicAnimation(keyPath: "strokeEnd")
        animation.duration = duration
        animation.fromValue = 0
        animation.toValue = 1
        animation.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseInEaseOut)
        circleLayer.strokeEnd = 1.0
        CATransaction.setCompletionBlock { 
            self.animateCircleEmpty(duration: duration)
        }
        // Do the actual animation
        circleLayer.add(animation, forKey: "animateCircle")
        CATransaction.commit()
    }
}

func animateCircleEmpty(duration: TimeInterval){
    if self.isAnimating{
        CATransaction.begin()
        let animation = CABasicAnimation(keyPath: "strokeEnd")
        animation.duration = duration
        animation.fromValue = 1
        animation.toValue = 0
        animation.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseInEaseOut)
        circleLayer.strokeEnd = 0
        CATransaction.setCompletionBlock {
            self.animateCircleFull(duration: duration)
        }
        // Do the actual animation
        circleLayer.add(animation, forKey: "animateCircle")
        CATransaction.commit()
    }
}

为了让它更加漂亮，你可以像这样改变动画的方向：

 func setCircleClockwise(){
    let circlePath = UIBezierPath(arcCenter: CGPoint(x: frame.size.width / 2.0, y: frame.size.height / 2.0), radius: (frame.size.width - 10)/2, startAngle: 0.0, endAngle: CGFloat(M_PI * 2.0), clockwise: true)
    self.circleLayer.removeFromSuperlayer()
    self.circleLayer = formatCirle(circlePath: circlePath)
    self.layer.addSublayer(self.circleLayer)
}

func setCircleCounterClockwise(){
    let circlePath = UIBezierPath(arcCenter: CGPoint(x: frame.size.width / 2.0, y: frame.size.height / 2.0), radius: (frame.size.width - 10)/2, startAngle: 0.0, endAngle: CGFloat(M_PI * 2.0), clockwise: false)
    self.circleLayer.removeFromSuperlayer()
    self.circleLayer = formatCirle(circlePath: circlePath)
    self.layer.addSublayer(self.circleLayer)
}

func formatCirle(circlePath: UIBezierPath) -> CAShapeLayer{
    let circleShape = CAShapeLayer()
    circleShape.path = circlePath.cgPath
    circleShape.fillColor = UIColor.clear.cgColor
    circleShape.strokeColor = UIColor.red.cgColor
    circleShape.lineWidth = 10.0;
    circleShape.strokeEnd = 0.0
    return circleShape
}

func animate(duration: TimeInterval){
    self.isAnimating = true
    self.animateCircleFull(duration: 1)
}

func endAnimate(){
    self.isAnimating = false
}

func animateCircleFull(duration: TimeInterval) {
    if self.isAnimating{
        CATransaction.begin()
        let animation = CABasicAnimation(keyPath: "strokeEnd")
        animation.duration = duration
        animation.fromValue = 0
        animation.toValue = 1
        animation.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseInEaseOut)
        circleLayer.strokeEnd = 1.0
        CATransaction.setCompletionBlock {
            self.setCircleCounterClockwise()
            self.animateCircleEmpty(duration: duration)
        }
        // Do the actual animation
        circleLayer.add(animation, forKey: "animateCircle")
        CATransaction.commit()
    }
}

func animateCircleEmpty(duration: TimeInterval){
    if self.isAnimating{
        CATransaction.begin()
        let animation = CABasicAnimation(keyPath: "strokeEnd")
        animation.duration = duration
        animation.fromValue = 1
        animation.toValue = 0
        animation.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseInEaseOut)
        circleLayer.strokeEnd = 0
        CATransaction.setCompletionBlock {
            self.setCircleClockwise()
            self.animateCircleFull(duration: duration)
        }
        // Do the actual animation
        circleLayer.add(animation, forKey: "animateCircle")
        CATransaction.commit()
    }
}

答案 4 :(得分：3)

更新@Mike S对 Swift 5

的回答

适用于frame manually，storyboard setup，autolayout setup 

class CircleView: UIView {

    let circleLayer: CAShapeLayer = {
        // Setup the CAShapeLayer with the path, colors, and line width
        let circle = CAShapeLayer()
        circle.fillColor = UIColor.clear.cgColor
        circle.strokeColor = UIColor.red.cgColor
        circle.lineWidth = 5.0

        // Don't draw the circle initially
        circle.strokeEnd = 0.0
        return circle
    }()

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

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

    func setup(){
        backgroundColor = UIColor.clear

        // Add the circleLayer to the view's layer's sublayers
        layer.addSublayer(circleLayer)
    }

    override func layoutSubviews() {
        super.layoutSubviews()
        // Use UIBezierPath as an easy way to create the CGPath for the layer.
        // The path should be the entire circle.
        let circlePath = UIBezierPath(arcCenter: CGPoint(x: frame.size.width / 2.0, y: frame.size.height / 2.0), radius: (frame.size.width - 10)/2, startAngle: 0.0, endAngle: CGFloat(Double.pi * 2.0), clockwise: true)

        circleLayer.path = circlePath.cgPath
    }

    func animateCircle(duration t: TimeInterval) {
        // We want to animate the strokeEnd property of the circleLayer
        let animation = CABasicAnimation(keyPath: "strokeEnd")

        // Set the animation duration appropriately
        animation.duration = t

        // Animate from 0 (no circle) to 1 (full circle)
        animation.fromValue = 0
        animation.toValue = 1

        // Do a linear animation (i.e. the speed of the animation stays the same)
        animation.timingFunction = CAMediaTimingFunction(name: CAMediaTimingFunctionName.linear)

        // Set the circleLayer's strokeEnd property to 1.0 now so that it's the
        // right value when the animation ends.
        circleLayer.strokeEnd = 1.0

        // Do the actual animation
        circleLayer.add(animation, forKey: "animateCircle")
    }
}

用法：

frame manually，storyboard setup，autolayout setup的示例代码

class ViewController: UIViewController {

    @IBOutlet weak var circleV: CircleView!

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

    @IBAction func animateFrame(_ sender: UIButton) {


        let diceRoll = CGFloat(Int(arc4random_uniform(7))*30)
        let circleEdge = CGFloat(200)

        // Create a new CircleView
        let circleView = CircleView(frame: CGRect(x: 50, y: diceRoll, width: circleEdge, height: circleEdge))

        view.addSubview(circleView)

        // Animate the drawing of the circle over the course of 1 second
        circleView.animateCircle(duration: 1.0)


    }

    @IBAction func animateAutolayout(_ sender: UIButton) {

        let circleView = CircleView(frame: CGRect.zero)
        circleView.translatesAutoresizingMaskIntoConstraints = false
        view.addSubview(circleView)
        circleView.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true
        circleView.centerYAnchor.constraint(equalTo: view.centerYAnchor).isActive = true
        circleView.widthAnchor.constraint(equalToConstant: 250).isActive = true
        circleView.heightAnchor.constraint(equalToConstant: 250).isActive = true
        // Animate the drawing of the circle over the course of 1 second
        circleView.animateCircle(duration: 1.0)
    }

    @IBAction func animateStoryboard(_ sender: UIButton) {
        // Animate the drawing of the circle over the course of 1 second
        circleV.animateCircle(duration: 1.0)

    }

}

答案 5 :(得分：2)

不仅可以对UIView进行子类化，还可以对CALayer进行子类化

换句话说，CoreAnimation的strokeEnd正常。经常调用CALayer的draw（在ctx：中）也可以

圆线帽很好

111

关键是要覆盖CALayer的方法action(forKey:)

动作定义图层的动态行为。例如，图层的可设置动画的属性通常具有相应的动作对象以启动实际的动画。当该属性更改时，该图层将查找与该属性名称关联的操作对象并执行该对象。

CAShapeLayer的内部子类

/**
 The internal subclass for CAShapeLayer.
 This is the class that handles all the drawing and animation.
 This class is not interacted with, instead
 properties are set in UICircularRing

 */
class UICircularRingLayer: CAShapeLayer {

    // MARK: Properties
    @NSManaged var val: CGFloat

    let ringWidth: CGFloat = 20
    let startAngle = CGFloat(-90).rads

    // MARK: Init

    override init() {
        super.init()
    }

    override init(layer: Any) {
        guard let layer = layer as? UICircularRingLayer else { fatalError("unable to copy layer") }

        super.init(layer: layer)
    }

    required init?(coder aDecoder: NSCoder) { return nil }

    // MARK: Draw

    /**
     Override for custom drawing.
     Draws the ring 
     */
    override func draw(in ctx: CGContext) {
        super.draw(in: ctx)
        UIGraphicsPushContext(ctx)
        // Draw the rings
        drawRing(in: ctx)
        UIGraphicsPopContext()
    }

    // MARK: Animation methods

    /**
     Watches for changes in the val property, and setNeedsDisplay accordingly
     */
    override class func needsDisplay(forKey key: String) -> Bool {
        if key == "val" {
            return true
        } else {
            return super.needsDisplay(forKey: key)
        }
    }

    /**
     Creates animation when val property is changed
     */
    override func action(forKey event: String) -> CAAction? {
        if event == "val"{
            let animation = CABasicAnimation(keyPath: "val")
            animation.fromValue = presentation()?.value(forKey: "val")
            animation.timingFunction = CAMediaTimingFunction(name: CAMediaTimingFunctionName.easeInEaseOut)
            animation.duration = 2
            return animation
        } else {
            return super.action(forKey: event)
        }
    }


    /**
     Draws the ring for the view.
     Sets path properties according to how the user has decided to customize the view.
     */
    private func drawRing(in ctx: CGContext) {

        let center: CGPoint = CGPoint(x: bounds.midX, y: bounds.midY)

        let radiusIn: CGFloat = (min(bounds.width, bounds.height) - ringWidth)/2
        // Start drawing
        let innerPath: UIBezierPath = UIBezierPath(arcCenter: center,
                                                   radius: radiusIn,
                                                   startAngle: startAngle,
                                                   endAngle: toEndAngle,
                                                   clockwise: true)

        // Draw path
        ctx.setLineWidth(ringWidth)
        ctx.setLineJoin(.round)
        ctx.setLineCap(CGLineCap.round)
        ctx.setStrokeColor(UIColor.red.cgColor)
        ctx.addPath(innerPath.cgPath)
        ctx.drawPath(using: .stroke)

    }


    var toEndAngle: CGFloat {
        return (val * 360.0).rads + startAngle
    }


}

辅助方法

/**
 A private extension to CGFloat in order to provide simple
 conversion from degrees to radians, used when drawing the rings.
 */
extension CGFloat {
    var rads: CGFloat { return self * CGFloat.pi / 180 }
}

使用带有内部自定义CALayer的UIView子类

@IBDesignable open class UICircularRing: UIView {

    /**
     Set the ring layer to the default layer, casted as custom layer
     */
    var ringLayer: UICircularRingLayer {
        return layer as! UICircularRingLayer
    }

    /**
     Overrides the default layer with the custom UICircularRingLayer class
     */
    override open class var layerClass: AnyClass {
        return UICircularRingLayer.self
    }

    /**
     Override public init to setup() the layer and view
     */
    override public init(frame: CGRect) {
        super.init(frame: frame)
        // Call the internal initializer
        setup()
    }

    /**
     Override public init to setup() the layer and view
     */
    required public init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
        // Call the internal initializer
        setup()
    }

    /**
     This method initializes the custom CALayer to the default values
     */
    func setup(){
        // Helps with pixelation and blurriness on retina devices
        ringLayer.contentsScale = UIScreen.main.scale
        ringLayer.shouldRasterize = true
        ringLayer.rasterizationScale = UIScreen.main.scale * 2
        ringLayer.masksToBounds = false

        backgroundColor = UIColor.clear
        ringLayer.backgroundColor = UIColor.clear.cgColor
        ringLayer.val = 0
    }


    func startAnimation() {
        ringLayer.val = 1
    }
}

用法：

class ViewController: UIViewController {

    let progressRing = UICircularRing(frame: CGRect(x: 100, y: 100, width: 250, height: 250))


    override func viewDidLoad() {
        super.viewDidLoad()
        view.addSubview(progressRing)
    }

    @IBAction func animate(_ sender: UIButton) {

        progressRing.startAnimation()

    }


}

带有指示器图像以设置角度

enter image description here

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