The Smart App Banner will allow your mobile visitors to get a link directly to your app on the App Store.
This banner will appear to all your visitors who are on an iPhone:
Go to https://tapcart.co/account and copy your App ID (in the ‘Account Information’ section)
Go to shopify.com/admin
Click on ‘Mobile App’ in the left sidebar
Paste your App ID in the iOS Smart Banners section (in the ‘App Store ID’ section)