当视频在AVPlayer中播放时，我想逐帧提取视频中的所有图像

import AVFoundation

func extractFramesFromVideo(url: URL) {
    let asset = AVAsset(url: url)
    guard let videoTrack = asset.tracks(withMediaType: .video).first else {
        print("No video track found in the asset.")
        return
    }
    
    let reader = try! AVAssetReader(asset: asset)
    let output = AVAssetReaderTrackOutput(track: videoTrack, outputSettings: nil)
    output.alwaysCopiesSampleData = false
    reader.add(output)
    
    reader.startReading()
    
    var frameCount = 0
    
    while let sampleBuffer = output.copyNextSampleBuffer() {
        let image = imageFromSampleBuffer(sampleBuffer: sampleBuffer)
        // 处理每一帧的图像，可以保存为图片文件或者进行其他操作
        // ...
        
        frameCount += 1
    }
    
    print("Total frames extracted: \(frameCount)")
}

func imageFromSampleBuffer(sampleBuffer: CMSampleBuffer) -> UIImage? {
    guard let imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer) else {
        return nil
    }
    
    CVPixelBufferLockBaseAddress(imageBuffer, .readOnly)
    
    let baseAddress = CVPixelBufferGetBaseAddress(imageBuffer)
    let bytesPerRow = CVPixelBufferGetBytesPerRow(imageBuffer)
    let width = CVPixelBufferGetWidth(imageBuffer)
    let height = CVPixelBufferGetHeight(imageBuffer)
    let colorSpace = CGColorSpaceCreateDeviceRGB()
    
    let bitmapInfo = CGBitmapInfo(rawValue: CGImageAlphaInfo.noneSkipFirst.rawValue | CGBitmapInfo.byteOrder32Little.rawValue)
    let context = CGContext(data: baseAddress, width: width, height: height, bitsPerComponent: 8, bytesPerRow: bytesPerRow, space: colorSpace, bitmapInfo: bitmapInfo.rawValue)
    
    guard let cgImage = context?.makeImage() else {
        return nil
    }
    
    let image = UIImage(cgImage: cgImage)
    
    CVPixelBufferUnlockBaseAddress(imageBuffer, .readOnly)
    
    return image
}

// 使用示例
let videoURL = URL(fileURLWithPath: "path/to/video.mp4")
extractFramesFromVideo(url: videoURL)