SAML - 从身份提供程序获取响应

我正在尝试使用 onelogin.com 实现SAML身份验证系统，我正在使用这个php库 https://github.com/simplesamlphp/saml2 和下面的代码

    // Set up an AuthnRequest
    $request = new SAML2_AuthnRequest();
    // $request->setId(SAML2_Utils::generateId());
    $request->setIssuer('http://localhost:8888/yii2/dw/advanced/frontend/web/index.php?r=site/auth');
    $request->setDestination('https://app.onelogin.com/trust/saml2/http-post/sso/418578');
    // Send it off using the HTTP-Redirect binding
    $binding = new SAML2_HTTPRedirect();
    $binding->send($request);

上面的代码成功地对我进行身份验证并将我回发到我的成功页面，但我不知道如何从发布的数据中获取用户信息。

我正在尝试下面的代码来获取用户数据

    $response = new 'SAML2_Response();
    print_r($response);

它给出了以下数据

SAML2_Response Object
(
[assertions:SAML2_Response:private] => Array
    (
    )
[inResponseTo:SAML2_StatusResponse:private] => 
[status:SAML2_StatusResponse:private] => Array
    (
        [Code] => urn:oasis:names:tc:SAML:2.0:status:Success
        [SubCode] => 
        [Message] => 
    )
[extensions:protected] => 
[tagName:SAML2_Message:private] => Response
[id:SAML2_Message:private] => _afe4d7fd7add270de7d334231e2eec68d1492363130
[issueInstant:SAML2_Message:private] => 14340322405
[destination:SAML2_Message:private] => 
[consent:SAML2_Message:private] => urn:oasis:names:tc:SAML:2.0:consent:unspecified
[issuer:SAML2_Message:private] => 
[relayState:SAML2_Message:private] => 
[document:protected] => 
[signatureKey:SAML2_Message:private] => 
[messageContainedSignatureUponConstruction:protected] => 
[certificates:SAML2_Message:private] => Array
    (
    )
[validators:SAML2_Message:private] => Array
    (
    )
 )

从上面的输出中，我无法获取用户信息，请帮助。