How to manage Codeigniter session with Ionic 3 application?

I have developed Codeigniter back-end and I want to use same controllers with Ionic 3 application. Ionic 3 login works perfect with back-end controller and creates session and I store user data in the session variable. When I access another controller via Ionic 3 after login success, it has no any user data in the session. I need to keep session data until it destroy on logout because user data is used in each controller access whether user is logged in or not. Here is my code.

//main login function
function user_login(){

    //Allow Cross origin

    $username = $this->input->post('username');
    $password = MD5($this->input->post('password'));

    $data = array('status'=>false,'message'=>'','data'=>'');

    //check a session exists,if not create new
        $user_data = array(
                'username' => $username,
                'attempts' => 0,
                'logged_in' => false

    $attempts = $this->session->userdata('attempts'); //get number of tried attempts

    $this->session->set_userdata('attempts',($attempts + 1));//increse number of attempts from one

        $lognError = $this->login_model->get_data_from_login_error_table($username);
        $b = true;

        if(sizeof($lognError) > 0){

            $trialsCount = $lognError['trials_count']; //get number of attempts that tried

            if($trialsCount >= 25){

                $b = false;

        if($b == true){

            $is_login = $this->login_model->login($username,$password);

            if($is_login != null) {

                $this->session->set_userdata('loged_in', true);
                $this->session->set_userdata('user_details', $user_details);
            } else {
                $data['status'] = false;
                $data['message'] = 'Incorrect username or password';

    // }
    echo json_encode($data);

//Checking whether user logged or not

public function is_login(){

    $details = $this->session->userdata('username');
    $is_loged_in = $this->session->userdata('loged_in');

    if(!$details || !$is_loged_in) {

$this->session->userdata(‘username’); returns null when I access via Ionic 3 but works fine with browser. How can I use PHP backend with ionic 3?

Help me out to solve this problem. Thanks in advanced.