how to send file from rest server to client on the response?

Code:

{"login":"login success!","user_admin_id":"18","projects":[{"id":"15","uid":"1","clientUID":"18","dateCreation":"2013-03-18 15:30:49","projectName":"My Dream House","adress1":"Aiguille du Midi","adress2":"3842 meters","postcode":"74400","city":"Chamonix","country":"FR","descriptive":"



\n\tPerfect spot for ski!<\/p>\n","avatar":"af605bd9daf75d754b4d1135e8349e1a.jpg","status":"1"}]}

Code:

function login_post()

    {





 $remember = (bool) $this->post('remember');

 if ($this->ion_auth->login($this->post('email'), $this->post('password'), $remember))

        {



          $projects=array();

          $user_id=$this->projects_model->check_user_id();

          ////get user_id

          $group = 'architect';

          $groupmember ='members';

          if($this->ion_auth->in_group($group))

          {

           //get all projects for the admin architect

             $status=1; //open

           $projects=$this->projects_model->get_myprojects_admin($status,$this->session->userdata('user_id'));



          }elseif ($this->ion_auth->in_group($groupmember))

          {



           //get only assigned projects

           $status=1; //open



           $projects=$this->projects_model->get_myprojects_emp($status,$this->session->userdata('user_id'));



          }





 $this->response(array('login' => 'login success!','user_admin_id'=>$user_id,'projects'=>$projects), 200);









        }else

        {

        

                 $this->response(array('error' => 'Couldn\'t login!'), 404);

         

        }





    }