PHPExcel从模板创建pdf

Question

我想使用以下代码从模板中使用php excel生成pdf文件：

 //load our new PHPExcel library
        $this->load->library('excel');
        echo 'Library load succesfull';
//name the worksheet
        $objPHPexcel = PHPExcel_IOFactory::load('/Applications/MAMP/htdocs/timesheet/files/Timesheet_template.xlsx');
        echo 'Loading template successfull...';
        $objWorksheet = $objPHPexcel->getActiveSheet();
               $objWorksheet->getCell('C17')->setValue($td_3);
        $objWorksheet->getCell('D17')->setValue($td_4);
        $objWorksheet->getCell('E17')->setValue($td_5);
        $objWorksheet->getCell('F17')->setValue($td_6);

         $month = date('F');
        $year = date('Y');

        $data['user_data'] = $this->session->userdata('user');

        $user_id = $data['user_data']["employee_id"];
        $f_name = $data['user_data']["f_name"];
        $s_name = $data['user_data']["s_name"];
        $username = $data['user_data']["user_name"];
        $title = $data['user_data']["title"];
        $is_active = $data['user_data']["is_active"];
        $employee_type = $data['user_data']["employee_type"];
        // $filename = 'just_some_random_name.xlsx'; //save our workbook as this file name
//save it to Excel5 format (excel 2003 .XLS file), change this to 'Excel2007' (and adjust the filename extension, also the header mime type)
//if you want to save it as .XLSX Excel 2007 format
        echo 'ALMOST CREATING THE PDF FILE';
        $objWriter = PHPExcel_Settings::PDF_RENDERER_DOMPDF;
        $rendererLibrary = 'domPDF0.6.0beta3';
        $rendererLibraryPath = '/Applications/MAMP/htdocs/timesheet/system/helpers/dompdf';
        $objWriter = PHPExcel_Settings::PDF_RENDERER_DOMPDF;
        $rendererLibrary = 'domPDF0.6.0beta3';
        $rendererLibraryPath = '/Applications/MAMP/htdocs/timesheet/system/helpers/dompdf';
        if (!PHPExcel_Settings::setPdfRenderer(
                        $objWriter, $rendererLibraryPath
                )) {
            die(
                    'Please set the $rendererName and $rendererLibraryPath values' .
                    PHP_EOL .
                    ' as appropriate for your directory structure'
            );
        }

        echo 'pdf creation almost starting';
        // $objWriter = PHPExcel_IOFactory::createWriter($objPHPexcel,'pdf');
        $objWriter = new PHPExcel_Writer_PDF($objPHPexcel);
        echo 'SUCCESS FULLY CREATED THE  PDF FILE...';
        $under_score = "_";
        $year = preg_replace('/\s+/', '', $year);

        $inputFileType = $username . $under_score . $month . $under_score . $year . ".pdf";


        $objWriter->save("files/un_approved/" . $username . $under_score . $month . $under_score . $year . ".pdf");

我正在使用dompdf库将最终模板转换为pdf，但生成的文件已损坏且无法由Adobe Reder打开。请告知我应该采用的最佳方式是什么？