Adding linear animation to shape layer

AddLinearAnimation.swift

// Create shape layer and add the path to it
let layer = CAShapeLayer()
layer.path = path.cgPath

// Set up the appearance of the shape layer
layer.strokeEnd = 0
layer.lineWidth = 1
layer.strokeColor = UIColor.black.cgColor
layer.fillColor = UIColor.clear.cgColor

// Create view and set its appearance
let view = UIView(frame: CGRect(x: 0, y: 0, width: 150, height: 150))
view.backgroundColor = .white

// Add the shape layer to view
view.layer.addSublayer(layer)

// Create the animation for the shape view
let animation = CABasicAnimation(keyPath: "strokeEnd")
animation.toValue = 1
animation.duration = 2 // seconds
animation.autoreverses = true
animation.repeatCount = .infinity

// And finally add the linear animation to the shape!
layer.add(animation, forKey: "line")

https://blog.thefuntasty.com/swift-stroke-animations-e1b864917255