Login Screen visiblity even after the user is login

[Mastermind-sap]

Issue :

• login page showing again and again , even after the user has already login into an app.
  Requires :

on the spash screen , Before navigating to login page , you should check whether the user has already login or not . If user has already login then user should navigate to nav_page ( file name already there ). Else user should navigate to login page.
Use shared preferences .