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

$fb = new Facebook([
  'app_id' => '{app-id}',
  'app_secret' => '{app-secret}',
  //'default_access_token' => '{access-token}', // optional
]);

// Use one of the helper classes to get a Facebook\Entities\AccessToken entity.
//   Facebook\Helpers\FacebookRedirectLoginHelper
//   Facebook\Helpers\FacebookJavaScriptLoginHelper
//   Facebook\Helpers\FacebookCanvasLoginHelper
//   Facebook\Helpers\FacebookPageTabHelper

try {
  // Get the Facebook\GraphNodes\GraphUser object for the current user:
  $response = $fb->get('/me', '{access-token}');
  $me = $response->getGraphUser();
  echo 'Logged in as ' . $me->getName();
} catch(FacebookResponseException $e) {
  // When Graph returns an error
  echo 'Graph returned an error: ' . $e->getMessage();
} catch(FacebookSDKException $e) {
  // When validation fails or other local issues
  echo 'Facebook SDK returned an error: ' . $e->getMessage();
}