Force download excel file using PHPExcel

Question

I'm using following headers to output excel sheet generated through PHPExcel:

// Redirect output to a client’s web browser (Excel2007)
header('Content-Type: application/vnd.ms-excel');
header('Content-Disposition: attachment;filename="01simple.xlsx"');
header('Cache-Control: max-age=0');

$objWriter = PHPExcel_IOFactory::createWriter($objPHPExcel, 'Excel2007');
$objWriter->save('php://output'); 

Instead gibberish text is sent to the browser:

PK������&DG�D�X��������[Content_Types].xml��MN�0���"�%nY ��vAa  �(0����ؖg�w{&i�@�nbE�{��y��d۸l
    m�����X�(���)���F��;@1_�����c)j�x/%��E��y�

Could anyone help me with proper headers to force download an excel file? Many thanks.

Edit 1:

header('Content-Type: application/vnd.openxmlformats-officedocument.spreadsheetml.sheet');
header('Content-Disposition: attachment;filename="01simple.xlsx"');
header('Cache-Control: max-age=0');

$objWriter = PHPExcel_IOFactory::createWriter($objPHPExcel, 'Excel2007');
$objWriter->save('php://output'); 

Still not working

Answer 1

Wrong Content Type and Filetype won't help:

application/vnd.ms-excel is for .xls files created with the Excel5 Writer

application/vnd.openxmlformats-officedocument.spreadsheetml.sheet is used for .xlsx files created with the Excel2007 Writer

But if you're seeing that gibberish (which is actually the xlsx file itself) in the browser, then the chances are that you're echoing or printing something else to the browser as well, even if it's only a whitespace character like a space, tab or newline before you send those headers