I have two apps developed by me. I want to LOGIN in my "A" app from my "B" app's credentials. So when user click on button "Login from B" then it should login from "B" and if app "B" is not already logged in then it shall open the "B" app and then User needs to login and then minimise the "B" app and return it to "A" app.
Example:- Login from Facebook.
How to do it?