첨부파일 다운로드

// Create destination URL
            let documentsUrl:URL =  FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first as URL!
            //let destinationFileUrl = documentsUrl.appendingPathComponent(filename)
            let destinationFileUrl = documentsUrl.appendingPathComponent(filename)

            //Create URL to the source file you want to download
            //let fileURL = URL(string: url)
            let fileURL = URL(string: url)

            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)")
                    }

                    do {
                        try FileManager.default.copyItem(at: tempLocalUrl, to: destinationFileUrl)
                        print("destinationFileUrl :  \(destinationFileUrl)")

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

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