如何配置Google API验证器(重定向URL值)?

我想让用户使用他们的谷歌帐户连接到我的Xamarin Forms应用程序。我一直在学习本教程: https://www.syncfusion.com/blogs/post/google-login-integration-in-xamarin-forms-a-complete-guide.aspx

重定向URL值中应该包含什么?现在我有“400错误:invalid_request”。我可能应该在某个地方注册那个页面?那个页面应该是什么?我想在登录后获取用户信息,并将其重定向到主应用程序页面(主页())。

我有这个代码:

    Xamarin.Auth.OAuth2Authenticator authenticator = null;
    private void SignInGoogleClicked(object sender, EventArgs e)
    {
        authenticator
            = new Xamarin.Auth.OAuth2Authenticator
            (
                clientId: "498923533154-uefrhbk3i9v7nqd7lep9lqb85u783m7v.apps.googleusercontent.com",
                scope: "https://www.googleapis.com/auth/userinfo.profile https://www.googleapis.com/auth/userinfo.email https://www.googleapis.com/auth/cloud-healthcare",
                authorizeUrl: new Uri("https://accounts.google.com/o/oauth2/auth"),
                redirectUrl:
                new Func<Uri>
                (
                    () =>
                    {
                        string uri = null;
                        switch (Xamarin.Forms.Device.RuntimePlatform)
                        {
                            case "Android":
                                uri =
                                    "com.xamarin.traditional.standard.samples.oauth.providers.android:/oauth2redirect"
                                    //"com.googleusercontent.apps.1093596514437-uefrhbk3i9v7nqd7lep9lqb85u783m7v:/oauth2redirect"
                                    ;
                                break; 
                            case "iOS":
                                uri =
                                    "com.xamarin.traditional.standard.samples.oauth.providers.ios:/oauth2redirect"
                                    //"com.googleusercontent.apps.1093596514437-cajdhnien8cpenof8rrdlphdrboo56jh:/oauth2redirect"
                                    ;
                                break;
                            case "Windows":
                                uri =
                                    "com.xamarin.traditional.standard.samples.oauth.providers.ios:/oauth2redirect"
                                    //"com.googleusercontent.apps.1093596514437-cajdhnien8cpenof8rrdlphdrboo56jh:/oauth2redirect"
                                    ;
                                break;
                        }

                        return new Uri(uri);
                    }
                ).Invoke(),
                getUsernameAsync: null,
                isUsingNativeUI: false
            )
            {
                AllowCancel = true,
            };

        NavigateLoginPage();
    }

    Xamarin.Auth.XamarinForms.AuthenticatorPage login_page = null;

    private void NavigateLoginPage()
    {
        login_page = new Xamarin.Auth.XamarinForms.AuthenticatorPage()
        {
            Authenticator = authenticator,
        };
        Navigation.PushAsync(login_page);
    }