shadow.swift

func createPulse() {
        
    for _ in 0...2 {
        let circularPath = UIBezierPath(arcCenter: .zero, radius: UIScreen.main.bounds.size.width/2.0, startAngle: 0, endAngle: 2 * .pi, clockwise: true)

        let pulseLayer1 = CAShapeLayer()
            pulseLayer1.path = circularPath.cgPath

            pulseLayer1.fillColor = UIColor.clear.cgColor
            pulseLayer1.lineCap = CAShapeLayerLineCap.round
            pulseLayer1.position = CGPoint(x: view.frame.size.width/2.0 - 2, y: view.frame.size.height/2.0)
            pulseLayer1.masksToBounds = false
            pulseLayer1.shouldRasterize = true

            //Shadow 1
            pulseLayer1.shadowOpacity = 1
            pulseLayer1.shadowColor = UIColor(red: 199/255, green: 216/255, blue: 229/255, alpha: 1.0).cgColor
            pulseLayer1.shadowOffset = CGSize(width: 11, height: 1)
            pulseLayer1.shadowRadius = 16
            pulseLayer1.shadowPath = UIBezierPath(roundedRect: circularPath.bounds, cornerRadius: UIScreen.main.bounds.size.width/2.0).cgPath

        let pulseLayer2 = CAShapeLayer()
            pulseLayer2.path = circularPath.cgPath

            pulseLayer2.fillColor = UIColor.clear.cgColor
            pulseLayer2.lineCap = CAShapeLayerLineCap.round
            pulseLayer2.position = CGPoint(x: 0, y: 0)
            pulseLayer2.masksToBounds = false
            pulseLayer2.shouldRasterize = true

            //Shadow 2
            pulseLayer2.shadowOpacity = 1
            pulseLayer2.shadowColor = UIColor(red: 244/255, green: 248/255, blue: 251/255, alpha: 0.5).cgColor
            pulseLayer2.shadowOffset = CGSize(width: -10, height: 0)
            pulseLayer2.shadowRadius = 10
            pulseLayer2.shadowPath = UIBezierPath(roundedRect: circularPath.bounds, cornerRadius: UIScreen.main.bounds.size.width/2.0).cgPath

        let pulseLayer3 = CAShapeLayer()
            pulseLayer3.path = circularPath.cgPath

            pulseLayer3.fillColor = UIColor.clear.cgColor
            pulseLayer3.lineCap = CAShapeLayerLineCap.round
            pulseLayer3.position = CGPoint(x: 0, y: 0)
            pulseLayer3.masksToBounds = false
            pulseLayer3.shouldRasterize = true

            //Shadow 3
            pulseLayer3.shadowOpacity = 1
            pulseLayer3.shadowColor = UIColor(red: 246/255, green: 251/255, blue: 255/255, alpha: 0.25).cgColor
            pulseLayer3.shadowOffset = CGSize(width: -10, height: -36)
            pulseLayer3.shadowRadius = 33
            pulseLayer3.shadowPath = UIBezierPath(roundedRect: circularPath.bounds, cornerRadius: UIScreen.main.bounds.size.width/2.0).cgPath

        let pulseLayer4 = CAShapeLayer()
            pulseLayer4.path = circularPath.cgPath

            pulseLayer4.fillColor = UIColor.clear.cgColor
            pulseLayer4.lineCap = CAShapeLayerLineCap.round
            pulseLayer4.position = CGPoint(x: 0, y: 0)
            pulseLayer4.masksToBounds = false
            pulseLayer4.shouldRasterize = true

            //Shadow 4
            pulseLayer4.shadowOpacity = 1
            pulseLayer4.shadowColor = UIColor(red: 255/255, green: 255/255, blue: 255/255, alpha: 0.2).cgColor
            pulseLayer4.shadowOffset = CGSize(width: -8, height: -8)
            pulseLayer4.shadowRadius = 14
            pulseLayer4.shadowPath = UIBezierPath(roundedRect: circularPath.bounds, cornerRadius: UIScreen.main.bounds.size.width/2.0).cgPath


        pulseLayer1.addSublayer(pulseLayer2)
        pulseLayer1.addSublayer(pulseLayer3)
        pulseLayer1.addSublayer(pulseLayer4)
        self.view.layer.addSublayer(pulseLayer1)

        self.pulseLayers.append(pulseLayer1)

    }
    DispatchQueue.main.asyncAfter(deadline: .now() + 0.6) {
        self.animatePulse(index: 0)
        DispatchQueue.main.asyncAfter(deadline: .now() + 0.8) {
            self.animatePulse(index: 1)
            DispatchQueue.main.asyncAfter(deadline: .now() + 1.0) {
                self.animatePulse(index: 2)
            }
        }
    }
}