Simple infinite spinner or loader in Swift

Spinner.swift

func drawAndRotateHollowCircle() {
    // draw
    let circlePath = UIBezierPath(arcCenter: CGPoint(x: 50, y: 50) , radius: CGFloat(10), startAngle: CGFloat(0), endAngle: CGFloat(Double.pi * 2 * 0.75), clockwise: true)
    let shapeLayer = CAShapeLayer()
    shapeLayer.path = circlePath.cgPath
    if let rect = shapeLayer.path?.boundingBoxOfPath {
        shapeLayer.frame = rect
        shapeLayer.bounds = rect
    }
    shapeLayer.fillColor = UIColor.clear.cgColor
    shapeLayer.strokeColor = UIColor.gray.cgColor
    shapeLayer.lineWidth = 3
    view.layer.addSublayer(shapeLayer)
    
    // rotate
    let rotationTransform = CATransform3DMakeRotation(.pi, 0, 0, 1)
    let rotationAnimation = CABasicAnimation(keyPath: "transform")
    rotationAnimation.toValue = NSValue(caTransform3D: rotationTransform)
    rotationAnimation.duration = 0.5
    rotationAnimation.isCumulative = true
    rotationAnimation.repeatCount = HUGE
    shapeLayer.add(rotationAnimation, forKey: "transform")
}