Thanks, this is very useful. I will try it today. One problem I observed , safari on iOS does not show pop up to create home screen icon:- quick Google gave me SO thread with following :-
Note on the “Add to Home screen: Safari has its own spec for “Home screen icon” called apple-mobile-web-app-capable in the meta tags. Web App Manifest Generator has a fallback for iOS using this meta tags.
iOS safari also does not load offline :/