在moviePlayerController中隐藏ActivityIndi​​cator

import UIKit
import MediaPlayer

class ViewController: UIViewController {
    var moviePlayerController: MPMoviePlayerController!
    var activityIndicator: UIActivityIndicatorView!

    override func viewDidLoad() {
        super.viewDidLoad()

        // 创建moviePlayerController对象
        moviePlayerController = MPMoviePlayerController(contentURL: URL(string: "https://example.com/video.mp4"))

        // 设置moviePlayerController的frame
        moviePlayerController.view.frame = CGRect(x: 0, y: 0, width: 300, height: 200)

        // 创建activityIndicator对象
        activityIndicator = UIActivityIndicatorView(style: .gray)
        activityIndicator.center = moviePlayerController.view.center

        // 将activityIndicator添加到moviePlayerController的视图中
        moviePlayerController.view.addSubview(activityIndicator)

        // 将moviePlayerController的视图添加到当前视图中
        view.addSubview(moviePlayerController.view)

        // 监听视频加载状态
        NotificationCenter.default.addObserver(self, selector: #selector(videoLoadStateDidChange), name: NSNotification.Name.MPMoviePlayerLoadStateDidChange, object: nil)
    }

    @objc func videoLoadStateDidChange(notification: NSNotification) {
        let loadState = moviePlayerController.loadState

        // 判断视频加载状态
        if loadState.contains(.unknown) || loadState.contains(.stalled) {
            // 显示加载指示器
            activityIndicator.startAnimating()
        } else {
            // 隐藏加载指示器
            activityIndicator.stopAnimating()
        }
    }
}