无法在iOS swift中打开下载的pdf路径?

我正在尝试实现pdf下载选项一旦用户点击下载选项pdf文件应该下载并打开。我尝试了以下链接,但不起作用 Saving PDF Files with Swift in iOS and display them 我尝试了以下代码。作为回应,它显示了我使用该路径所经过的路径,但我没有找到任何文件。

 @objc func downloadPdfFile(_ sender : UIButton)
    {
        var localDic :NSDictionary!
        localDic = totalSyllabusArray.object(at: sender.tag) as! NSDictionary
        let filepath = localDic["filepath"] as! String
        let pdfURLString:String = FETCH_InMegh_Image_BaseURL + filepath
        let documentsUrl:URL =  FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first as URL!
        let destinationFileUrl = documentsUrl.appendingPathComponent("downloadedFile.pdf")
        //Create URL to the source file you want to download
        let fileURL = URL(string: pdfURLString)
        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)
                } 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()
    }