下載swift 3中的文件只能完成24 kb？使用URLSession

Question

我正在使用此guide下載文件在swift 3.我試圖通過添加一個特定的循環來操縱它，以便能夠下載n個文件。它可以工作，但它只能完成24 kb。

這裏是我的代碼：

for jsonDict in data{ 
    var jasonData = Attachment() 

    if let data = (jsonDict["url"] as? String) {jasonData.url = data} else { jasonData.url = ""} 

    self.beginDownloadFile(jasonData: jasonData) 
} 

func beginDownloadFile(jasonData: Attachment){ 
     let identifier = jasonData.customer_id + "/attachment/" + jasonData.patient_guid + "@%E%@" + "/" + jasonData.filename + "@%E%@" + jasonData.customer_id + "@%E%@" + jasonData.patient_guid 

     let backgroundSessionConfiguration = URLSessionConfiguration.background(withIdentifier: identifier) 

     backgroundSession = Foundation.URLSession(configuration: backgroundSessionConfiguration, delegate: self, delegateQueue: OperationQueue.main) 

     var link = self.constants.PATIENTS_PICTURE_LINK + jasonData.customer_id + "/attachment/" + jasonData.guid + "/" + jasonData.filename 
     link = link.replacingOccurrences(of: " ", with: "%20") 

     let url = URL(string: link)! 

     downloadTask = backgroundSession.downloadTask(with: url) 
     downloadTask.resume() 
    } 

    func urlSession(_ session: URLSession, 
        downloadTask: URLSessionDownloadTask, 
        didFinishDownloadingTo location: URL){ 
     let string_container = session.configuration.identifier!.components(separatedBy: "@%E%@") 

     let folderPath = string_container[0] 
     let fileName = string_container[1] 
     let customerID = string_container[2] 
     let patientGUID = string_container[3] 

     print("GUID IS: " + patientGUID) 

     let path = NSSearchPathForDirectoriesInDomains(FileManager.SearchPathDirectory.documentDirectory, FileManager.SearchPathDomainMask.userDomainMask, true) 
     let documentDirectoryPath:String = path[0] 

     let fileManager = FileManager() 

     let path1 = documentDirectoryPath.stringByAppendingPathComponent(pathComponent: customerID) 
     let path2 = path1.stringByAppendingPathComponent(pathComponent: "attachment") 
     let path3 = path2.stringByAppendingPathComponent(pathComponent: patientGUID) 

     let destinationURLForFile = URL(fileURLWithPath: path3.appendingFormat(fileName)) 

     do { 
      if !fileManager.fileExists(atPath: path1) { 
       try fileManager.createDirectory(atPath: path1, withIntermediateDirectories: false, attributes: nil) 
      } 
      if !fileManager.fileExists(atPath: path2) { 
       try fileManager.createDirectory(atPath: path2, withIntermediateDirectories: false, attributes: nil) 
      } 

      if !fileManager.fileExists(atPath: path3) { 
       try fileManager.createDirectory(atPath: path3, withIntermediateDirectories: false, attributes: nil) 
      } 

     } catch let error as NSError { 
      print("ATTACHMENT ERROR: " + error.localizedDescription); 
     } 

     if fileManager.fileExists(atPath: destinationURLForFile.path){ 
      //showFileWithPath(path: destinationURLForFile.path) 
      do { 
       try fileManager.removeItem(at: destinationURLForFile) 
       try fileManager.moveItem(at: location, to: destinationURLForFile) 
       //showFileWithPath(path: destinationURLForFile.path) 
      }catch{ 
       print("An error occurred while moving/deleting file to destination url") 
      } 
     } 
     else{ 
      do { 
       try fileManager.moveItem(at: location, to: destinationURLForFile) 
       //showFileWithPath(path: destinationURLForFile.path) 
      }catch{ 
       print("An error occurred while moving file to destination url") 
      } 
     } 
    } 

結果：

Sample Screenshot

是什麼原因導致它停止@ 24 KB？是因爲循環？或標識符操作？

Answer 1

哪裏是您聲明的代碼downloadTask？它是一個實例屬性？

如果是這樣，那麼你的指針每次扔掉至downloadTask循環運行，而這段代碼獲得RAN：

downloadTask = backgroundSession.downloadTask(with: url) downloadTask.resume()

有可能是你的任務被提前釋放，因爲這。如果是這樣的話，那麼最後時間通過循環下載應該完成。

另外，是否有可能24k是正確的文件大小？或者可能是一個靜態錯誤頁面的大小？