在Swift中将视频保存到本地(目录)？

guard let documentsDirectory = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first else { return }
let videoURL = documentsDirectory.appendingPathComponent("myVideo.mp4")

do {
    let assetWriter = try AVAssetWriter(outputURL: videoURL, fileType: .mp4)
    let videoSettings = [
        AVVideoCodecKey: AVVideoCodecType.h264,
        AVVideoWidthKey: 640,
        AVVideoHeightKey: 480
    ]
    let assetWriterInput = AVAssetWriterInput(mediaType: .video, outputSettings: videoSettings)
    
    if assetWriter.canAdd(assetWriterInput) {
        assetWriter.add(assetWriterInput)
    } else {
        // 添加输入失败
        return
    }
    
    // 开始写入
    assetWriter.startWriting()
} catch {
    // 创建 AVAssetWriter 失败
    return
}

let pixelBufferAdaptor = AVAssetWriterInputPixelBufferAdaptor(assetWriterInput: assetWriterInput, sourcePixelBufferAttributes: nil)

assetWriterInput.requestMediaDataWhenReady(on: DispatchQueue.global(qos: .background)) {
    while assetWriterInput.isReadyForMoreMediaData {
        // 获取下一帧视频数据
        if let nextFrame = getNextVideoFrame() {
            if let pixelBuffer = nextFrame.pixelBuffer {
                // 将视频帧数据添加到 AVAssetWriterInput
                pixelBufferAdaptor.append(pixelBuffer, withPresentationTime: nextFrame.presentationTime)
            }
        } else {
            // 所有视频帧数据已写入
            assetWriterInput.markAsFinished()
            assetWriter.finishWriting {
                if assetWriter.status == .completed {
                    // 视频保存成功
                } else {
                    // 视频保存失败
                }
            }
            break
        }
    }
}