使用URLSession下载视频后连续将视频保存在文档目录中

Question

我想从远程网址下载并播放视频。首先，我使用 url 会话下载视频，下载后，将视频保存到文档目录，然后从文档目录播放视频。但是使用这种方法，我必须等到整个视频下载完成，然后才能将其保存到文档目录并播放。但我想要实现的是，我想将下载的视频部分连续保存到文档目录，以便我可以从文档目录连续播放它，而不必等到整个视频下载完成。那么有什么方法可以连续下载部分视频，以便将其保存到文档目录中。是否有任何 url 会话代表可以给我已经下载的部分或其他东西。

我使用 url 会话进行下载，并且 didFinishDownloadingTo 仅在下载完成后调用。下面是我到目前为止尝试过的代码。

public func downloadVideo(url: URL) {

    let downloadTask = URLSession.shared.downloadTask(with: url) { (location, response, error) in
        if let error = error {
            print("Download error: \(error)")
            return
        }
        
        guard let location = location else { return }
        do {
            let data = try Data(contentsOf: location)
            print("downloaded data: \(data)")
            
        } catch {
            print("Error appending downloaded data: \(error)")
        }
    }
    downloadTask.resume()
}}

extension MediaCacheManager: URLSessionDownloadDelegate {

public func urlSession(_ session: URLSession, downloadTask: URLSessionDownloadTask, didFinishDownloadingTo location: URL) {
    guard let data = try? Data(contentsOf: location) else {
        return
    }

    guard let applicationSupportDirectory = FileManager.default.urls(for: .applicationSupportDirectory, in: .userDomainMask).first else {
        print("Application Support directory not found")
        return
    }
    
    // Create a subdirectory within Application Support, if needed
    let subdirectoryURL = applicationSupportDirectory.appendingPathComponent("telehealthVideo")
    do {
        try FileManager.default.createDirectory(at: subdirectoryURL, withIntermediateDirectories: true, attributes: nil)
    } catch {
        print("Error creating subdirectory: \(error.localizedDescription)")
        return
    }
    
    let destinationURL = subdirectoryURL.appendingPathComponent("myVideo.mp4")
    do {
        print("destinationURL \(destinationURL)")
        try data.write(to: destinationURL)
        //saveVideoToAlbum(videoURL: destinationURL, albumName: "MyAlbum")
    } catch {
        print("Error saving file:", error)
    }}

public func urlSession(_ session: URLSession, downloadTask: URLSessionDownloadTask, didWriteData bytesWritten: Int64, totalBytesWritten: Int64, totalBytesExpectedToWrite: Int64) {
    
    print(Float(totalBytesWritten) / Float(totalBytesExpectedToWrite))
    DispatchQueue.main.async {
       
        self.progress = (Float(totalBytesWritten) / Float(totalBytesExpectedToWrite))
        debugPrint("progress \(self.progress)")
    }
}}

Answer 1

只是为您指明正确的方向。您需要首先查看您的数据存储（后端）。通常，您不能只获取 URL 并下载文件大小的 10%，并期望它是视频的前 10%。