How to display custom error message without using codeigniter session flashdata - codeigniter

Question

On my project I am trying to create a error message for my session. I am trying to make it so that if session redirects to main page then will echo message that is on login controller.
Note: I am trying not to use session flashdata if possible. I
already know how to use flashdata.
When I login to my dashboard it displays token in url
Example http://localhost/project-session/index.php/dashboard/32118fa09a0ef2df16851d1f35e3f7d5
On my dashboard __construct() I have this code below.
if ($this->session->userdata('user_id') == FALSE) {
redirect('/');
}
The code above redirects session to home if token is false.
And if it has been redirected because session expires then below message should be activated, On login controller
$get_url_token = $this->uri->segment(2);
$get_session_token = $this->session->userdata('token');
if ((isset($get_session_token) && !isset($get_url_token)) || ((isset($get_url_token) && (isset($get_session_token) && ($get_url_token != $get_session_token))))) {
echo "Session Token Invalid";
}
Login Controller
<?php
defined('BASEPATH') OR exit('No direct script access allowed');
class Welcome extends CI_Controller {
public function index()
{
$this->load->library('form_validation');
$this->load->library('encryption');
$key = bin2hex($this->encryption->create_key(16));
$get_url_token = $this->uri->segment(2);
$get_session_token = $this->session->userdata('token');
if ((isset($get_session_token) && !isset($get_url_token)) || ((isset($get_url_token) && (isset($get_session_token) && ($get_url_token != $get_session_token))))) {
echo "Session Token Invalid";
}
$this->form_validation->set_rules('username', 'Username');
$this->form_validation->set_rules('password', 'Password');
if ($this->form_validation->run() == FALSE) {
$this->load->view('welcome_message');
} else {
$data = array(
'token' => $key
);
$this->session->set_userdata($data);
redirect('dashboard' .'/'. $key);
}
}
}
Question: Without using codeigniter session flashdata how can I echo my message in my login controller when it is redirect to login because session expire. When I am redirect the echo message does not get activated.
Updated Login Controller
I have got message working but when I go to reload page it does not clear message. Any Suggestions.
<?php
defined('BASEPATH') OR exit('No direct script access allowed');
class Welcome extends CI_Controller {
private $error = array();
public function index() {
$this->load->library('form_validation');
$this->load->library('encryption');
$key = bin2hex($this->encryption->create_key(16));
$this->form_validation->set_rules('username', 'Username');
$this->form_validation->set_rules('password', 'Password');
if ($this->form_validation->run() == TRUE) {
$this->session->set_userdata(array('token' => $key));
redirect('dashboard' .'/'. $key);
}
$get_url_token = $this->uri->segment(2);
$get_session_token = $this->session->userdata('token');
if ((isset($get_session_token) && !isset($get_url_token)) || ((isset($get_url_token) && (isset($get_session_token) && ($get_url_token != $get_session_token))))) {
$this->error['warning'] = 'Session Token';
}
if (isset($this->error['warning'])) {
$data['error_warning'] = $this->error['warning'];
} else {
$data['error_warning'] = '';
}
$this->load->view('welcome_message', $data);
}
}