Playground Timer

timer.swift

//: A UIKit based Playground for presenting user interface
  
import UIKit
import AVFoundation
import PlaygroundSupport

let arcPoint = CGPoint(x: 170, y: 200)

func BezierPath(center: CGPoint) -> CGPath {
    
    let path = UIBezierPath(arcCenter: center, radius: 100, startAngle: -CGFloat.pi / 2, endAngle: CGFloat.pi + CGFloat.pi, clockwise: true)
    return path.cgPath
}

class ViewController: UIViewController {
    
    var shapeLayer: CAShapeLayer = {
        var shapeLayer = CAShapeLayer()
        shapeLayer.path = BezierPath(center: arcPoint)
        shapeLayer.fillColor = UIColor.clear.cgColor
        shapeLayer.strokeColor = UIColor.white.cgColor
        shapeLayer.lineWidth = 20
        shapeLayer.lineCap = kCALineCapRound
        shapeLayer.strokeEnd = 0
        return shapeLayer
    }()
    
    var shapeBackground: CAShapeLayer = {
        var shapeBackground = CAShapeLayer()
        shapeBackground.path = BezierPath(center: arcPoint)
        shapeBackground.fillColor = UIColor.clear.cgColor
        shapeBackground.strokeColor = UIColor.white.cgColor
        shapeBackground.lineWidth = 20
        shapeBackground.opacity = 0.3
        return shapeBackground
    }()
    
    let superView: UIView = {
        var view = UIView()
        view.frame = CGRect(x: 50, y: 100, width: 350, height: 500)
        view.backgroundColor = .black
        return view
    }()
    
    override func viewDidLoad() {
        super.viewDidLoad()
        self.view.addSubview(self.superView)
        self.superView.layer.addSublayer(self.shapeBackground)
        self.superView.layer.addSublayer(self.shapeLayer)
        
        self.superView.addGestureRecognizer(UITapGestureRecognizer(target: self, action: #selector(ViewController.onTap)))
    }
    
    @objc func onTap() {
        print("Tapped!")
        var basicAnimation = CABasicAnimation(keyPath: "strokeEnd")
        basicAnimation.fillMode = kCAFillModeForwards
        basicAnimation.toValue = 1
        basicAnimation.speed = 0.1
        basicAnimation.isRemovedOnCompletion = false
        self.shapeLayer.add(basicAnimation, forKey: "strokeEnd animation")
    }
}

// Present the view controller in the Live View window
PlaygroundPage.current.liveView = ViewController()