How does iOS determine if a site has an app?

Question

Apple App Store

We are talking about this:

When you visit some popular resources - the browser automatically reports the presence of the application in the Store (but not for all).
Interested in how to achieve this? (since this form is the same for everyone and in the case of an installed application, it offers to open it - I think the implementation of this is hardcoded in the OS)

Answer 1

Implementing a Smart App Banner on Your Website
https://developer.apple.com/library/ios/documentat...
Apple has great documentation actually)

Answer 2

My inner kopetan hints that the site is looking at what kind of OS you have and offers you to download the APP.