Login behaviours

I have a client which is asking different behaviours on a user logging in for first time or it is logging in for second time.. If the user login for the first time the view should be a login view where users put its username and password and second time it should not ask for username and password. I stored the username and password in app properties but then it is never showing the login view even after a clean build. Any help on how can i acheive this..Sorry if it is a trivial thing..Thanks in advance.

can you provide some sample code, because the approach you have outlined seems like it should be working?

in app.js

var userName = Ti.App.Properties.getString('username');
    alert(userName);// **shows the user name even after clean build**
    //construct UI
    if(userName ==''){
    Ti.include('ui/common/LoginView.js');
    } else {
    Ti.include('ui/common/View2.js');
    }

Ti.App.Properties.setString('username', loginField.value);
    Ti.App.Properties.setString('password', passwordField.value)

I stored the username and password in app properties but then it is never showing the login view even after a clean build.

App properties are not removed after a clean build. Only after an app uninstall.