如何从iOS上的视频中获取帧

import AVFoundation

func extractFramesFromVideo(videoURL: URL) -> [UIImage]? {
    let asset = AVAsset(url: videoURL)
    let imageGenerator = AVAssetImageGenerator(asset: asset)
    var frames: [UIImage] = []
    
    // 设置生成图像的属性
    imageGenerator.appliesPreferredTrackTransform = true
    let time = CMTimeMake(value: 1, timescale: 60) // 每秒获取一帧
    
    do {
        let totalSeconds = CMTimeGetSeconds(asset.duration)
        let totalFrames = Int(totalSeconds) * 60 // 每秒60帧
        for i in 0..<totalFrames {
            let currentTime = CMTimeMake(value: Int64(i), timescale: 60)
            let imageRef = try imageGenerator.copyCGImage(at: currentTime, actualTime: nil)
            let image = UIImage(cgImage: imageRef)
            frames.append(image)
        }
        return frames
    } catch {
        print("提取视频帧失败：\(error)")
        return nil
    }
}

// 使用示例
if let videoURL = Bundle.main.url(forResource: "sample", withExtension: "mp4") {
    let frames = extractFramesFromVideo(videoURL: videoURL)
    // 处理获取到的视频帧
    if let frames = frames {
        for frame in frames {
            // 处理每一帧图像
        }
    }
}