从文档中的视频获取缩略图的问题

Question

我正在尝试从存储在文档目录中的视频文件生成缩略图。首先，我只收集mp4 格式的视频文件：

 override func viewWillAppear(_ animated: Bool) {

        let VIDEO = [collect(files: "mp4"),
                     collect(files: "MP4")]
        videoArray = Array(VIDEO.joined())

    }


 func collect(files:String) -> [String] {

        var fileExtentions = [String]()

        let documentsUrl =  FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first!

        let fileManager = FileManager.default
        let keys = [URLResourceKey.isDirectoryKey, URLResourceKey.localizedNameKey]
        let options: FileManager.DirectoryEnumerationOptions = [.skipsPackageDescendants, .skipsSubdirectoryDescendants, .skipsHiddenFiles]

        let enumerator = fileManager.enumerator(
            at: documentsUrl,
            includingPropertiesForKeys: keys,
            options: options,
            errorHandler: {(url, error) -> Bool in
                return true
        })


        if enumerator != nil {
            while let file = enumerator!.nextObject() {
                let path = URL(fileURLWithPath: (file as! URL).absoluteString, relativeTo: documentsUrl).path
                if path.hasSuffix(files){
                    fileExtentions.append(path)
                }
            }
        }


        return fileExtentions
    }

然后像这样填充tableview的数据：

 func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {

        let cell = tableView.dequeueReusableCell(withIdentifier: "Cell", for: indexPath) as! VideoCell

        let files = videoArray[indexPath.row]
        let fileURL = URL(fileURLWithPath: files)

        //Vido Title
        cell.videoTitle.text = fileURL.lastPathComponent.removingPercentEncoding!


        cell.thumbnail.image = getThumbnailFrom(path:fileURL)

        return cell
    }

我正在从这样的视频中生成缩略图：

  func getThumbnailFrom(path: URL) -> UIImage? {

        do {

            let asset = AVURLAsset(url: path , options: nil)
            let imgGenerator = AVAssetImageGenerator(asset: asset)
            imgGenerator.appliesPreferredTrackTransform = true
            let cgImage = try imgGenerator.copyCGImage(at: CMTimeMake(0, 5), actualTime: nil)
            let thumbnail = UIImage(cgImage: cgImage)

            return thumbnail

        } catch let error {

            print("*** Error generating thumbnail: \(error.localizedDescription)")
            return nil

        }

    }

但最后在运行应用程序时，编译器给了我这个错误：

*** 生成缩略图时出错：在此服务器上找不到请求的 URL。

Answer 1

最后找到正确的URL来解决问题：

let documentsURL = NSURL(fileURLWithPath: NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true).first!,isDirectory: true ) 

let urlToMyPath = documentsURL.appendingPathComponent(fileURL.lastPathComponent.removingPercentEncoding!)!

Answer 2

@Mc.Lover 从我这边测试了 getThumbnailFrom() 函数。它在我身边工作得很好。可能您可能需要检查路径 url 是否正确。否则，您拥有的视频文件集可能存在问题。

下面是我测试的代码。

func getThumbnailFrom() -> UIImage? {

    do {
        let path = Bundle.main.path(forResource: "Video_05", ofType:"mp4")!
        let asset = AVURLAsset(url: URL.init(fileURLWithPath: path) , options: nil)
        let imgGenerator = AVAssetImageGenerator(asset: asset)
        imgGenerator.appliesPreferredTrackTransform = true
        let cgImage = try imgGenerator.copyCGImage(at: CMTimeMake(0, 5), actualTime: nil)
        let thumbnail = UIImage(cgImage: cgImage)

        return thumbnail

    } catch let error {

        print("*** Error generating thumbnail: \(error.localizedDescription)")
        return nil

    }

}