Classe para acessar OpenGraph do Facebook usando app e secret id e pegar os últimos posts de uma página.

FacebookMicroSDK.php

<?php

/*
 * FacebookMicroSDK
 * @Author: Lucas Farina
 * @Author URI: http://www.lucasfarina.com.br
 * @Version 0.0.1
 * */

class FacebookMicroSDK {

    /*
     * Initialize Variables
     * */
    private $fbid;
    private $fbsecret;
    private $accessToken;

    function __construct() {
        $this->fbid = "920685888038410";
        $this->fbsecret = "b4f41c61af9327373a353bfbc61881ff";
        $this->accessToken = $this->getAccessToken($this->fbid, $this->fbsecret);
    }

    /*
    * Get Page ID
    * @Return  Integer
    * @Params  $pageNickname, $accessToken
    * */
    public function getPageId($pageNickname) {
        // GET
        $url = "https://graph.facebook.com/?ids=http://facebook.com/{$pageNickname}&fields=id&{$this->accessToken}";
        $request = file_get_contents($url);
        $arrayDecoded = json_decode($request, true);

        if(array_key_exists("http://facebook.com/{$pageNickname}",$arrayDecoded))
            return $arrayDecoded["http://facebook.com/{$pageNickname}"]["id"];
        else
            return null;
    }

    /*
     * Get LastPosts
     * @Return Json
     * @Params UserID or PageID and an valid accessToken
     * */
    public function loadFB($pageID){
        $url = "https://graph.facebook.com/v2.5/".$pageID."/feed?limit=3";

        // Update by MC Vooges 11jun 2014: Access token is now required:
        $url.= '&'.$this->accessToken;

        $request = file_get_contents($url);

        //return the data as an object
        return json_decode($request, true);
    }

    /*
     * Get Access Token
     * @Return  String
     * @Params  $appID, $appSecret
     * */
    private function getAccessToken($appID, $appSecret) {
        $token = 'https://graph.facebook.com/oauth/access_token?client_id='.$appID.'&client_secret='.$appSecret.'&grant_type=client_credentials';
        return file_get_contents($token); // returns 'accesstoken=APP_TOKEN|APP_SECRET'
    }
}

/*
 *  Example Call the MicroSDK
 * $myPosts = FacebookMicroSDK->loadFB(FacebookMicroSDK->getPageId("PAGENICK"));
 * */