[CodeIgniter]set_header

$this->output->set_header('X-Frame-Options: SAMEORIGIN');
$this->output->set_header('Cache-control: no-cache, no-store, post-check=0, pre-check=0');
$this->output->set_header('Pragma: no-cache');
$this->output->set_header('Expires: Thu, 01 Dec 1994 16:00:00 GMT');