Consider using apple-mobile-web-app-capable for the webapp.
This will make the webapp running like a native app (fullscreen, sandbox, outside of safari) on ios when adding it to home screen. IFTTT Platform webapp already has this and it’s awesome. Give it a try.
Here is the full tag:
<meta name=“apple-mobile-web-app-capable” content=“yes”>
More details here:
https://medium.com/appscope/designing-native-like-progressive-web-apps-for-ios-1b3cdda1d0e8