Codeigniter如何包含facebook sdk的首字母？

<?php
require_once APPPATH.'libraries/facebook-php-sdk-v5/autoload.php';

use Facebook\Facebook;
use Facebook\Exceptions\FacebookSDKException;

class CI_Facebook extends Facebook {
    public function __construct($config = array()) {
        $ci =& get_instance();
        $ci->config->load('facebook', TRUE);

        if (empty($config)) {
            $config = $ci->config->item('facebook');
        }

        parent::__construct($config);
    }
}

<?php
$config['facebook_app_id'] = 'YOUR_APP_ID';
$config['facebook_app_secret'] = 'YOUR_APP_SECRET';
$config['facebook_default_graph_version'] = 'v11.0';

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

class FacebookController extends CI_Controller {
    public function __construct() {
        parent::__construct();
        $this->load->library('facebook');
    }

    public function login() {
        $helper = $this->facebook->getRedirectLoginHelper();
        $loginUrl = $helper->getLoginUrl('YOUR_REDIRECT_URL', ['email', 'public_profile']);

        redirect($loginUrl);
    }

    public function callback() {
        $helper = $this->facebook->getRedirectLoginHelper();

        try {
            $accessToken = $helper->getAccessToken();
            $response = $this->facebook->get('/me?fields=id,name,email', $accessToken);
            $user = $response->getGraphUser();
            
            // 处理用户数据
        } catch(Facebook\Exceptions\FacebookResponseException $e) {
            // 处理异常
        } catch(Facebook\Exceptions\FacebookSDKException $e) {
            // 处理异常
        }
    }
}