Twitter登录：重定向不起作用

Question

我正在尝试使用Twitter oauth PHP库实现使用twitter api登录。一切似乎都很好。我获得了用户的Twitter登录屏幕。根据代码，我$twitteroauth->http_code为200。但它继续将页面重定向到相同的Twitter登录屏幕。 这是我的代码：

function loginTwitter()
    {  
        // The TwitterOAuth instance
        $twitteroauth = new TwitterOAuth('xxx', 'xxxxx');
        // Requesting authentication tokens, the parameter is the URL we will be redirected to
        $request_token = $twitteroauth->getRequestToken('http://localhost/testsaav/socialAuth/twitterAuth');

        // Saving them into the session
        $_SESSION['oauth_token'] = $request_token['oauth_token'];
        $_SESSION['oauth_token_secret'] = $request_token['oauth_token_secret'];

        // If everything goes well..
        if($twitteroauth->http_code==200){
            // Let's generate the URL and redirect
            $url = $twitteroauth->getAuthorizeURL($request_token['oauth_token']);
            header('Location: '. $url);
        } else {
            // It's a bad idea to kill the script, but we've got to know when there's an error.
            die('Something wrong happened.');
        }

    }