swift 获取视频缩略图

Question

取得本地视频之后，需要缩略图用于展示（需要获取到第0秒的图片）视频格式.mov和.mp4的

func getVideoImage(videoUrl: URL) -> UIImage {

    let avAsset = AVAsset.init(url: videoUrl)
    let generator = AVAssetImageGenerator.init(asset: avAsset)
    generator.appliesPreferredTrackTransform = true
    let time: CMTime = CMTimeMakeWithSeconds(0.0, 600) // 取第0秒， 一秒600帧
    var actualTime: CMTime = CMTimeMake(0, 0)
    let cgImage: CGImage = try! generator.copyCGImage(at: time, actualTime: &actualTime)
    
    return UIImage.init(cgImage: cgImage)
}

let cgImage: CGImage = try! generator.copyCGImage(at: time, actualTime: &actualTime)
这一行报错
UserInfo={NSLocalizedDescription=unknown error, NSUnderlyingError=0x12d6f07c0 {Error Domain=NSOSStatusErrorDomain Code=-12935 "(null)"}}