从远程 url 下载 urlSession 失败 - 出现 CFNetworkDownload_gn6wzc.tmp

Question

我尝试使用 urlSession 从远程 url 下载文件。但是当下载完成时，出现了一个名为CFNetworkDownload_gn6wzc.tmp的意外文件，然后我无法使用uidocumentinteractioncontroller.打开那个文件那个文件是什么？如何解决这个问题。谢谢回复。

这是消息

Your location is file:///Users/pisal/Library/Developer/CoreSimulator/Devices/26089E37-D4EA-49E5-8D45-BB7D9C52087D/data/Containers/Data/Application/767E966E-5954-41BA-B003-90E2D27C5558/Library/Caches/com.apple.nsurlsessiond/Downloads/com.SamboVisal.downloadTask/CFNetworkDownload_gn6wzc.tmp

这是我的示例代码：我通过这种方法发送链接

@IBAction func startDownload(_ sender: Any) {
    let url = URL(string: "http://www.tutorialspoint.com/swift/swift_tutorial.pdf")!
    let task = DownloadManager.shared.activate().downloadTask(with: url)
    task.resume()

}

然后当下载完成时：

func urlSession(_ session: URLSession, downloadTask: URLSessionDownloadTask, didFinishDownloadingTo location: URL) {
        debugPrint("Download finished: \(location)")
        debugPrint("download task : \(downloadTask)")
        ViewController().documentInteraction(location: location)

    }

当我试图打开uidocumentinteractioncontroller时

let documentDirectoryPath = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true)[0] as NSString
    let destinationPath = documentDirectoryPath.appendingPathComponent("swift.pdf")
    let destinationUrl = URL(fileURLWithPath: destinationPath)

    do{
        try FileManager.default.copyItem(at: locat, to: destinationUrl)
    }
    catch {
        print("error copying file: \(error.localizedDescription)")
    }

    documentInteractionController.url = destinationUrl

    if !documentInteractionController.presentOpenInMenu(from: openButton.bounds, in: view, animated: true) {
        print("You don't have an app installed that can handle pdf files.")
    }

Answer 1

下载的数据存储在一个临时文件中。您需要将该数据写入文件并使用它。在func urlSession(_ session: URLSession, downloadTask: URLSessionDownloadTask, didFinishDownloadingTo location: URL)方法中编写如下代码：

func urlSession(_ session: URLSession, downloadTask: URLSessionDownloadTask, didFinishDownloadingTo location: URL) {
    debugPrint("Download finished: \(location)")
    do {
        let downloadedData = try Data(contentsOf: location)

        DispatchQueue.main.async(execute: {
            print("transfer completion OK!")

            let documentDirectoryPath = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true).first! as NSString
            let destinationPath = documentDirectoryPath.appendingPathComponent("swift.pdf")

            let pdfFileURL = URL(fileURLWithPath: destinationPath)
            FileManager.default.createFile(atPath: pdfFileURL.path,
                                           contents: downloadedData,
                                           attributes: nil)

            if FileManager.default.fileExists(atPath: pdfFileURL.path) {
                print("pdfFileURL present!") // Confirm that the file is here!
            }
        })
    } catch {
        print(error.localizedDescription)
    }
}

编辑

当从服务器下载任何文件时，您的应用会将所有数据保存在临时文件中。下载文件后，它会为您提供临时保存数据的 URL。现在由您决定如何以及在何处存储该数据。临时文件不存储在 Document 目录中。您需要将该文件的内容复制到具有正确扩展名的文件中。替换代码中的给定方法。当您想读取该文件时，请使用 swift.pdf 而不是 tmp 文件。