how to create gmail client for ios?

Question

I tried to make Gmail Client for iOS... I sucessfully retrived emails from Gmail server using IMAP and SMTP with the help of coremail 2. Every thing is fine.. I am asking for username and password in text field. but this is not a true way I think..
I tried other email client apps they show official gmail login page in there apps, so user can enter ther id in it and then app shows there emails from gmail. Also with my IMAP and SMTP access there is no my app in Accounts Google, which shows that which app is accessing which data of your Google Account. But other apps do show like below.

I found oAuth2 but lot of people talks that it is only use to add login feature in app, not for login and access gmail mails.

Here is what I want.. app will have a button called Login, when the user click on the button the gmail login page should be displayed, once the user provides his credentials, user will direct to Google registration page of the app with the details filled that are fetched from the gmail of the user.. (Details like user gmail mails, first and last name, email, contacts so on).... sorry for bad english...

Answer 1

Done using. OAuth 2.0 with the help of this answer. gmail integration in ios application . By using auth.scope = @"mail.gmail.com";