如何在swift中从图像创建循环加载器

import UIKit

class ViewController: UIViewController {
    
    var activityIndicator: UIActivityIndicatorView!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        // 创建UIImageView并设置图像
        let imageView = UIImageView(frame: CGRect(x: 0, y: 0, width: 100, height: 100))
        imageView.center = view.center
        imageView.image = UIImage(named: "your_image_name")
        view.addSubview(imageView)
        
        // 创建UIActivityIndicatorView并设置样式
        activityIndicator = UIActivityIndicatorView(style: .gray)
        activityIndicator.center = view.center
        view.addSubview(activityIndicator)
        
        // 开始动画
        activityIndicator.startAnimating()
        
        // 模拟加载延迟
        DispatchQueue.main.asyncAfter(deadline: .now() + 3) {
            // 停止动画
            self.activityIndicator.stopAnimating()
        }
    }
}