How to integrate a mobile application for a site with the site itself?

Question

Mobile development

There is an iOS mobile app for the site.
When opening a site in a browser, it is required to issue a line on top with the inscription "Application X is installed" and the "open" button if the application is installed.
Just as it suggests, for example VKontakte in the screenshot, Instagram also offers to open the application (it seems only in safari)
I don’t know how this is done, and in the application itself or in the browser?

Answer 1

drank or finish the API
but in general Here's a solution for you

Answer 2

https://github.com/jasny/jquery.smartbanner
Tested on iphone, everything is ok)