如何以给定的顺序动画/填充UIBezierPath？

import UIKit

func animatePath() {
    let path = UIBezierPath(rect: CGRect(x: 50, y: 50, width: 200, height: 200))
    
    let shapeLayer = CAShapeLayer()
    shapeLayer.path = path.cgPath
    shapeLayer.fillColor = UIColor.red.cgColor
    shapeLayer.strokeColor = UIColor.blue.cgColor
    shapeLayer.lineWidth = 2.0
    
    let view = UIView(frame: CGRect(x: 0, y: 0, width: 300, height: 300))
    view.layer.addSublayer(shapeLayer)
    
    let animation = CABasicAnimation(keyPath: "strokeEnd")
    animation.fromValue = 0.0
    animation.toValue = 1.0
    animation.duration = 2.0
    
    let animationGroup = CAAnimationGroup()
    animationGroup.animations = [animation]
    animationGroup.duration = 2.0
    
    shapeLayer.add(animationGroup, forKey: "pathAnimation")
}