iOS 获取视频的 第一帧 作为封面 Swift

    //MARK: 获取第一帧当封面
    static func getFirstGen(asset:AVURLAsset) -> UIImage? {
        let assetGen = AVAssetImageGenerator(asset: asset)
        assetGen.appliesPreferredTrackTransform = true
        let time = CMTimeMake(value: 0, timescale: 600)
        var actualTime:CMTime = .zero
        if let cgImage = try? assetGen.copyCGImage(at: time, actualTime: &actualTime) {
            let image = UIImage(cgImage: cgImage)
            return image
        }
        return nil
    }