GraphQL is a query language for the APIs for getting your data. It is an alternative for the REST APIs. It is not specific to a single platform and works for all type of clients including Android, iOS or the web. It stands between your server and client and helps you to query your data in a more optimized way.
If you would like to leverage Nosto's intelligence engine in your Android app, please see our example app and the docs.
Leveraging Nosto's intelligence engine on iOS is just as easy as on Android. While an example app is yet to be provided, please read the Apollo docs.