change MyBooksViewController to table view controller.
show preLoginView from Nib if isLogin variable is NO.
use mock data to show something on tableview if isLogin variable is YES.
change LoginViewController to MoreViewController
create a basic MoreViewController to show userinfo. Use NSUserDefaults to store username info, which will indicate login status.
click logout in MoreView to update user login status in NSUserDefaults, and update all views.
click login button to login