Codeigniter Facebook配置文件未加载

我有这个代码开始使用Facebook SDK V4和Codeigniter。这是库文件夹中Facebook SDK文件夹文件旁边的Facebook.php文件：

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

if ( session_status() == PHP_SESSION_NONE ) {
  session_start();
}

define('FACEBOOK_SDK_V4_SRC_DIR', APPPATH . 'libraries/facebook/Facebook');
require_once("autoload.php");

require_once( 'Facebook/FacebookSession.php' );
require_once( 'Facebook/FacebookRedirectLoginHelper.php' );
require_once( 'Facebook/FacebookRequest.php' );
require_once( 'Facebook/FacebookResponse.php' );
require_once( 'Facebook/FacebookSDKException.php' );
require_once( 'Facebook/FacebookRequestException.php' );
require_once( 'Facebook/FacebookAuthorizationException.php' );
require_once( 'Facebook/GraphObject.php' );
require_once( 'Facebook/Entities/AccessToken.php' );
require_once( 'Facebook/HttpClients/FacebookHttpable.php' );
require_once( 'Facebook/HttpClients/FacebookCurlHttpClient.php' );
require_once( 'Facebook/HttpClients/FacebookCurl.php' ); 

use Facebook\FacebookSession;
use Facebook\FacebookRedirectLoginHelper;
use Facebook\FacebookRequest;
use Facebook\FacebookResponse;
use Facebook\FacebookSDKException;
use Facebook\FacebookRequestException;
use Facebook\FacebookAuthorizationException;
use Facebook\GraphObject;
use Facebook\Entities\AccessToken;
use Facebook\HttpClients\FacebookHttpable;
use Facebook\HttpClients\FacebookCurlHttpClient;
use Facebook\HttpClients\FacebookCurl; 

class Facebook {
  var $ci;
  var $helper;
  var $session;
  var $permissions;

  public function __construct() {
    $this->ci =& get_instance();
    $this->permissions = $this->ci->config->item('permissions', 'facebook');

    echo $this->ci->config->item('api_id', 'facebook');

exit;

---

现在我的代码工作了。只增加了一行：

$this->ci->load->config('facebook'); // this is the line that I added

谢谢你的启发：）
你的代码如图所示毫无意义，你对
Facebook
的类定义甚至还没有完成。你是对的。我刚刚粘贴了我需要显示我所面临问题的部分。要添加到哪里，这一行？让我试试自动加载。
$this->ci->load->config('facebook'); // this is the line that I added