Android back button on a modal window close the APP

Ionic Framework ionic-v3
3

Not working, app exits on modal too.

I’d tried with this, but no luck

ionViewDidLoad() {
    console.log('ionViewDidLoad ModalPage');
    this.platform.registerBackButtonAction(() => {
      this.viewCtrl.dismiss();
    });
  }

from: Ionic hardware back button just in tabs pages - #2 by Chal131313