从服务器响应中提取访问变量

Question

我正忙于发送对请求令牌的HTTP curl请求，当我发送以下代码以获取访问令牌时，当我收到响应时，我希望访问令牌值而不是整个响应。

 $params = array(
                'username' => 'nuser',
                'password' => 'password',
           
            );

$curlSecondHandler = curl_init();

curl_setopt_array($curlSecondHandler, [
    CURLOPT_URL => 'https://localhost/api/v3/authentication/usernamepassword',
    CURLOPT_RETURNTRANSFER => true,
CURLOPT_POST => true,
    CURLOPT_HTTPHEADER => [
        'Content-Type: multipart/form-data',
        'Authorization: Bearer '
        
    ],
       CURLOPT_POSTFIELDS => $params,
      

    
]);


$response2 = curl_exec($curlSecondHandler);
curl_close($curlSecondHandler);


$arr = json_decode($response2);

echo $response2->data -> accessToken ;

我收到此错误

试图获取非对象的属性