SwiftUI视图出现时播放视频报错，如何等待资源加载后播放？

你遇到的错误是因为远程视频资源未加载完成时就调用了play()，导致主线程同步查询未就绪的媒体属性（PreferredTransform）被阻塞，慢速网络下问题会更突出。解决核心是监听AVPlayerItem的加载状态，等资源真正准备好后再触发播放。

核心思路 #

1. 改用AVPlayerItem管理远程媒体资源，替代直接用URL初始化AVPlayer的方式
2. 监听AVPlayerItem的status属性，仅当状态变为.readyToPlay时执行播放
3. 避免视图刚出现时强制播放，让资源加载完成后自动触发播放逻辑

修改后的完整代码 #

import SwiftUI
import AVKit
import Combine

struct MainVideoPlayer: View {
    let url: URL
    @State private var player: AVPlayer?
    @State private var cancellables = Set<AnyCancellable>()
    
    var body: some View {
        ZStack {
            VideoPlayer(player: $player)
        }
        .onAppear {
            setupPlayer()
        }
        .onDisappear {
            // 清理资源，避免内存泄漏
            player?.pause()
            player = nil
            cancellables.removeAll()
        }
    }
    
    private func setupPlayer() {
        let playerItem = AVPlayerItem(url: url)
        
        // 用Combine监听playerItem的状态变化
        playerItem.publisher(for: \.status)
            .receive(on: DispatchQueue.main)
            .sink { [weak self] status in
                guard let self = self else { return }
                switch status {
                case .readyToPlay:
                    // 资源准备完成，开始播放
                    self.player?.play()
                case .failed:
                    // 处理加载失败场景
                    if let error = playerItem.error {
                        print("视频加载失败: \(error.localizedDescription)")
                    }
                case .unknown:
                    // 资源加载中，等待即可
                    break
                @unknown default:
                    break
                }
            }
            .store(in: &cancellables)
        
        // 初始化player并关联playerItem
        player = AVPlayer(playerItem: playerItem)
    }
}

struct VideoPlayer: UIViewControllerRepresentable {
    @Binding var player: AVPlayer?
    
    func makeUIViewController(context: Context) -> AVPlayerViewController {
        let controller = AVPlayerViewController()
        controller.showsPlaybackControls = false
        controller.videoGravity = .resizeAspectFill
        return controller
    }
    
    func updateUIViewController(_ uiViewController: AVPlayerViewController, context: Context) {
        // 当player实例变化时更新控制器关联的player
        uiViewController.player = player
    }
}

关键修改点说明 #

• AVPlayerItem管理资源：通过AVPlayerItem可精准监听媒体加载状态，避免直接操作AVPlayer导致的主线程同步阻塞
• Combine状态监听：利用Combine框架监听status属性变化，确保在主线程处理状态回调，保证UI操作安全
• 资源清理：在视图消失时暂停播放并释放player，避免内存泄漏
• 错误处理：添加加载失败的逻辑分支，方便后续扩展用户提示

额外优化建议 #

• 可在资源加载中（status为.unknown时）添加加载指示器，提升用户体验
• 若需支持缓存，可通过AVAssetResourceLoader实现自定义资源加载逻辑

内容的提问来源于stack exchange，提问作者Ahmed Zaidan