How use compser in Codeigniter

My composer config is OK
I have problem only in Buzz or Firebase

I need an example code like this:

PHP Code:

<?php
defined('BASEPATH') OR exit('No direct script access allowed');
use \Firebase\JWT\JWT;

class Test extends CI_Controller {

 public function index()
 {
 $key = "example_key";
 $token = array(
 "iss" => "http://example.org",
 "aud" => "http://example.com",
 "iat" => 1356999524,
 "nbf" => 1357000000
 );

 $jwt = JWT::encode($token, $key);
 $decoded = JWT::decode($jwt, $key, array('HS256'));

 print_r($jwt);
 print_r($decoded);
 }
} 


This code works without error.

When i use require_once 'vendor/firebase/php-jwt/Firebase/PHP-JWT/Authentication/JWT.php';
and remove use \Firebase\JWT\JWT;
That is working good
Why?
I used autoload already

You use the 2.x or less Version and not the 5

My composer config is OK
I have problem only in Buzz or Firebase

I need an example code like this:

PHP Code:

<?php
defined('BASEPATH') OR exit('No direct script access allowed');
use \Firebase\JWT\JWT;

class Test extends CI_Controller {

 public function index()
 {
 $key = "example_key";
 $token = array(
 "iss" => "http://example.org",
 "aud" => "http://example.com",
 "iat" => 1356999524,
 "nbf" => 1357000000
 );

 $jwt = JWT::encode($token, $key);
 $decoded = JWT::decode($jwt, $key, array('HS256'));

 print_r($jwt);
 print_r($decoded);
 }
} 


This code works without error.

When i use require_once 'vendor/firebase/php-jwt/Firebase/PHP-JWT/Authentication/JWT.php';
and remove use \Firebase\JWT\JWT;
That is working good
Why?
I used autoload already

You use the 2.x or less Version and not the 5

No it is OK
My problem solved with remove use \Firebase\JWT\JWT