BorderAnimation.swift

@IBAction func buttonTapped(_ sender: UIButton) {
        let pathFrame = CGRect(x: -sender.bounds.midX, y: -sender.bounds.midY, width: sender.bounds.width, height: sender.bounds.height)
        let path = UIBezierPath(roundedRect: pathFrame, cornerRadius: sender.layer.cornerRadius)
        let shapePosition = self.view.convert(sender.center, from: self.view)
        
        let circleShape = CAShapeLayer()
        circleShape.path = path.cgPath
        circleShape.position = shapePosition
        circleShape.fillColor = UIColor.clear.cgColor
        circleShape.opacity = 0
        circleShape.strokeColor = UIColor.red.cgColor
        circleShape.lineWidth = 2
        
        self.view.layer.addSublayer(circleShape)
        
        let scaleAnimation = CABasicAnimation(keyPath: "transform.scale")
        scaleAnimation.fromValue = NSValue(caTransform3D: CATransform3DIdentity)
        scaleAnimation.toValue = NSValue(caTransform3D: CATransform3DMakeScale(2.5, 2.5, 1))
        
        let alphaAnimation = CABasicAnimation(keyPath: "opacity")
        alphaAnimation.fromValue = 1
        alphaAnimation.toValue = 0
        
        let animationGroup = CAAnimationGroup()
        animationGroup.animations = [scaleAnimation, alphaAnimation]
        animationGroup.duration = 0.5
        animationGroup.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseOut)
        circleShape.add(animationGroup, forKey: nil)
    }