cannot get previous page name on device using ionic2 - ionic2

Question

I am using ionic 2.
I update my ionic version.
Ionic version 3.4.0
If user not authenticated my root page is Login Page. after user logged in and go to dashboard Page.user When click on hardware back button go to Login Page.
I Need if user authenticated click on hardware back button does not go to Login page.Display msg "Do you want to exit?"
Because I need get previous page name.
I used this Code
this.navCtrl.last();
It's work fine on browser.But not work on device.
I run my app.
I consoled the value
t {_isHidden: false, willEnter: e, didEnter: e, willLeave: e, didLeave: e…}
and its return the page name is 't'.

Answer 1

Then you can pass the name of the current page while you route to a new page. Then you can use that name from new page.
Example (Assume we are routing from page A to page B)
in page A
this.navCtrl.push(B,{previousPage:'A'});
in page B
class B{
constructor(private navParams: NavParams) {
let previousPage= navParams.get('previousPage');
}
}
====UPDATE=======
I cant understand why you want previous page name for achieve this. any way your requirement can achieve as following.
in your app component set root page as loginPage.
public rootPage: any = LoginPage;
Then, If user login success. route to dashboard page by calling
navCtrl.setRoot(HomePage); // here user will route to the home page and set it as root
You can re change the root page as login page when user click sign out
navCtrl.setRoot(LoginPage);
then if user is authenticated root page will be HomePage and if user click back button user will leave the app.
Hope this will help you :) enjoy Ionic ;)