Lined circles shrinks and grows with glowing (changing alpha) in order around any view that you specialize.

LinePulsator.swift

import UIKit

class TestViewController: UIViewController {

    private var timer: Timer?
    private var circleShapeCount: Int = 0
    
    private var scaleAnimation: CABasicAnimation? = {
        let animation = CABasicAnimation(keyPath: "transform.scale")
        animation.fromValue = 0.80
        animation.toValue = 2.0
        animation.duration = 3.0
        animation.isRemovedOnCompletion = false
        animation.repeatCount = .infinity
        animation.timingFunction = CAMediaTimingFunction(name: .easeInEaseOut)
        return animation
    }()
    
    private var opacityAnimation: CABasicAnimation? = {
        let animation = CABasicAnimation(keyPath: "opacity")
        animation.fromValue = 1.0
        animation.toValue = 0
        animation.duration = 3.0
        animation.isRemovedOnCompletion = false
        animation.repeatCount = .infinity
        animation.timingFunction = CAMediaTimingFunction(name: .easeInEaseOut)
        return animation
    }()
    
    override func viewDidLoad() {
        super.viewDidLoad()

        view.backgroundColor = .cyan
    }
    
    override func viewDidAppear(_ animated: Bool) {
        super.viewDidAppear(animated)
        
        addPulseAnimation()
    }
    
    private func addPulseAnimation() {
        timer = Timer.scheduledTimer(timeInterval: 1.2,
                                         target: self,
                                         selector: #selector(createPulse),
                                         userInfo: nil, repeats: true)
        timer?.fire()
    }
    
    @objc private func createPulse() {
        
        if circleShapeCount < 3 {
            circleShapeCount += 1
            
            let circlePath = UIBezierPath(arcCenter: .zero,
                                          radius: 125,
                                          startAngle: 0.0,
                                          endAngle: CGFloat.pi * 2,
                                          clockwise: true)
            let circleLayer = CAShapeLayer()
            circleLayer.path = circlePath.cgPath
            circleLayer.lineWidth = 2
            circleLayer.strokeColor = UIColor.appRed.cgColor
            circleLayer.fillColor = UIColor.clear.cgColor
            circleLayer.lineCap = .round
            circleLayer.position = view.center
            view.layer.addSublayer(circleLayer)
            circleLayer.add(scaleAnimation!, forKey: "scaleAnimation")
            circleLayer.add(opacityAnimation!, forKey: "opacityAnimation")
            
        } else {
            timer?.invalidate()
            timer = nil
        }
    }