生成返回0 byte[]的视频缩略图的iOS代码

import AVFoundation

func generateThumbnail(from videoURL: URL) -> Data? {
    let asset = AVAsset(url: videoURL)
    let imageGenerator = AVAssetImageGenerator(asset: asset)
    imageGenerator.appliesPreferredTrackTransform = true
    
    var thumbnailData: Data?
    
    do {
        let thumbnailCGImage = try imageGenerator.copyCGImage(at: CMTimeMake(value: 0, timescale: 1), actualTime: nil)
        let thumbnailImage = UIImage(cgImage: thumbnailCGImage)
        
        if let thumbnailImageData = thumbnailImage.jpegData(compressionQuality: 1.0) {
            thumbnailData = thumbnailImageData
        }
    } catch {
        print("Error generating thumbnail: \(error)")
    }
    
    return thumbnailData
}