如何在完成后重启CABasicAnimation

import UIKit

class ViewController: UIViewController, CAAnimationDelegate {
    
    let animation = CABasicAnimation(keyPath: "position")
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        // 设置动画属性
        animation.fromValue = NSValue(cgPoint: CGPoint(x: 0, y: 0))
        animation.toValue = NSValue(cgPoint: CGPoint(x: 200, y: 200))
        animation.duration = 1.0
        
        // 设置代理对象
        animation.delegate = self
        
        // 添加动画到视图的layer
        view.layer.add(animation, forKey: "positionAnimation")
    }
    
    func animationDidStop(_ anim: CAAnimation, finished flag: Bool) {
        if flag {
            // 动画完成后重新设置起始值和结束值
            animation.fromValue = NSValue(cgPoint: CGPoint(x: 200, y: 200))
            animation.toValue = NSValue(cgPoint: CGPoint(x: 0, y: 0))
            
            // 重新启动动画
            view.layer.add(animation, forKey: "positionAnimation")
        }
    }
}