How should I develop Google OAuth 2 for iOS, and also with original google sign in UI?

Question

I am going to write an app for google services, but I stuck at the first step: let user sign in for google's services.

I can find gtm-OAuth2 library from Google's code base. But the problem for that is I don't know how to load Google's default sign in page - like some apps are doing (below is the screenshot):

Anyone gives me some hints?

Where can I load this page for iphone and how then to get the login info?

Answer 1

This page is provided by: the Google OAuth 2 login flow