如何下载多个URL并将其保存到文件管理器？

Question

我正在使用swift 3.0中的一个项目，我可以获得多个网址来保存。截至目前，我已能够将单个URL下载并保存到本地文件管理器。如何根据以下模块保存多个URL。我的代码适用于单个网址，如下所示。我该怎么改变？

public static func dowanloadFile (downloadURL: String, fileName:String, onCompletion:@escaping ()->Void, onError:@escaping ()->Void?){



    // Create destination URL
    let documentsUrl:URL =  FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first as URL!
    let destinationFileUrl = documentsUrl.appendingPathComponent(fileName + ".mp3")
    print("Dest Location: \(destinationFileUrl)")
    //Create URL to the source file you want to download
    let fileURL = URL(string: downloadURL)

    let sessionConfig = URLSessionConfiguration.default
    let session = URLSession(configuration: sessionConfig)

    let request = URLRequest(url:fileURL!)

    let task = session.downloadTask(with: request) { (tempLocalUrl, response, error) in
        if let tempLocalUrl = tempLocalUrl, error == nil {
            // Success
            if let statusCode = (response as? HTTPURLResponse)?.statusCode {

                print("Successfully downloaded. Status code: \(statusCode)")
                print("Path is :",destinationFileUrl)
                print("Path is Temp :",tempLocalUrl)
            }

            do {
                try FileManager.default.copyItem(at: tempLocalUrl, to: destinationFileUrl)
                onCompletion()

                print("dest :",destinationFileUrl)
                return

            } catch (let writeError) {
                print("Error creating a file \(destinationFileUrl) : \(writeError)")
            }

        } else {
            print("Error took place while downloading a file. Error description: %@", error?.localizedDescription ?? "error");
        }
        if(onError != nil){
            onError()
        }
    }
    task.resume()

}