Session cleared Automatically in Iphone using CI 2.x

PHP Code:

   $data = array(
                       'adminf_name'=>$fname,
                       'admin_name' =>$name,   
                       'admin_id'=>$id,
                       'is_logged_in' => true
                     );

 $this->session->set_userdata($data); 


I used this for store session values All are working fine when i used in Computer ,But the issue is The sesssion automatically cleared when i check  my app in iphone mode using google chrome ,same thing happen in iphone too ,Help Appreciated i m using codeigniter 2.X

The Issue Solved when i used this
$config['sess_match_useragent'] = FALSE;
Thank you