swift4 根据视频url和时间点截图

extension UIImage {
    /// 根据视频url和时间点截图
    static func thumbnailImageForVideo(videoURL: URL, time: TimeInterval) -> UIImage? {
        
        let asset = AVURLAsset.init(url: videoURL, options: nil)
        let assetImageGenerator = AVAssetImageGenerator(asset: asset)
        assetImageGenerator.appliesPreferredTrackTransform = true
        assetImageGenerator.apertureMode = AVAssetImageGeneratorApertureMode.encodedPixels
        let thumbnailCGImage: CGImage?
        let thumbnailImageTime: CFTimeInterval = time
        var thumbnailImage: UIImage?
        do {
            thumbnailCGImage = try assetImageGenerator.copyCGImage(at: CMTimeMake(Int64(thumbnailImageTime),60), actualTime: nil)
            if let cgImage = thumbnailCGImage {
                thumbnailImage = UIImage(cgImage: cgImage)
            }
            
        } catch {
            
        }
        
        return thumbnailImage
    }
}