如何在RealityKit的VideoMaterial中异步加载网络视频到AVPlayer

核心思路 #

1. 检测到参考图像后，先在主线程创建带占位材质（SimpleMaterial）的平面，立即添加到场景，避免用户看到卡顿或空白
2. 异步加载网络视频资源，将视频加载逻辑放到后台队列，不阻塞主线程
3. 视频加载完成后，切回主线程替换材质为VideoMaterial，再启动播放

修改后的完整代码 #

class Coordinator: NSObject, ARSessionDelegate {
    var parent: ARViewContainer
    var videoPlayer: AVPlayer?

    init(parent: ARViewContainer) {
        self.parent = parent
    }

    func session(_ session: ARSession, didAdd anchors: [ARAnchor]) {
        guard let imageAnchor = anchors.first as? ARImageAnchor,
              imageAnchor.name == "referenceimg1" else { return }
        
        // 1. 主线程创建占位平面（带SimpleMaterial），立即显示
        let planeSize = imageAnchor.referenceImage.physicalSize
        let placeholderMaterial = SimpleMaterial(
            color: .gray,
            isMetallic: false
        )
        let videoPlane = ModelEntity(
            mesh: .generatePlane(
                width: Float(planeSize.width),
                depth: Float(planeSize.height),
                cornerRadius: 10
            ),
            materials: [placeholderMaterial]
        )
        
        let anchorEntity = AnchorEntity(anchor: imageAnchor)
        anchorEntity.addChild(videoPlane)
        parent.arView.scene.addAnchor(anchorEntity)
        
        // 2. 后台队列异步加载视频，避免阻塞主线程
        DispatchQueue.global(qos: .userInitiated).async { [weak self] in
            guard let self = self,
                  let videoURL = URL(string: "https://swiftanytime-content.s3.ap-south-1.amazonaws.com/SwiftUI-Beginner/Video-Player/iMacAdvertisement.mp4") else { return }
            
            let playerItem = AVPlayerItem(url: videoURL)
            // 监听视频加载状态
            let statusObservation = playerItem.observe(\.status, options: [.new]) { [weak self, weak videoPlane] item, change in
                guard let self = self, let videoPlane = videoPlane else { return }
                
                DispatchQueue.main.async {
                    switch item.status {
                    case .readyToPlay:
                        // 3. 主线程替换为VideoMaterial并播放
                        self.videoPlayer = AVPlayer(playerItem: item)
                        let videoMaterial = VideoMaterial(avPlayer: self.videoPlayer!)
                        videoPlane.model?.materials = [videoMaterial]
                        self.videoPlayer?.play()
                    case .failed:
                        // 加载失败可添加错误处理，比如显示错误材质
                        let errorMaterial = SimpleMaterial(color: .red, isMetallic: false)
                        videoPlane.model?.materials = [errorMaterial]
                    case .unknown:
                        break
                    @unknown default:
                        break
                    }
                }
            }
            // 保留观察对象，避免被提前释放
            statusObservation.retain()
        }
    }
}

关键细节说明 #

• 异步加载：用DispatchQueue.global(qos: .userInitiated)将视频加载逻辑放到后台，主线程只负责UI相关操作，彻底解决卡顿
• 占位材质：先显示灰色SimpleMaterial，你可以根据需求修改颜色、添加纹理（比如加载动画图片）
• 状态监听：通过KVO监听AVPlayerItem的status属性，确保视频真正准备好后再替换材质，避免播放异常
• 弱引用处理：使用[weak self]和[weak videoPlane]避免循环引用，防止内存泄漏

内容的提问来源于stack exchange，提问作者user1207524