app.component.js

constructor(
    platform: Platform,
    public af: AngularFire,
    public loadingCtrl: LoadingController,
    public authData: AuthData,
    public storage: Storage,
    public menuCtrl: MenuController,
  ) {

    platform.ready().then(() => {
      // Okay, so the platform is ready and our plugins are available.
      // Here you can do any higher level native things you might need.


      this.storage.get('introShown').then((result) => {

        if (result) {

          const authObserver = af.auth.subscribe( user => {
            if (user) {
              this.user = af.database.object('/users/' + user.uid);
              this.rootPage = HomePage;
              authObserver.unsubscribe();
            } else {
              this.rootPage = LoginPage;
              authObserver.unsubscribe();
            }
          });

        } else {
          this.rootPage = IntroPage;
          this.storage.set('introShown', true);
        }

      });

      StatusBar.styleDefault();
      Splashscreen.hide();
    });
  }