Patterns and practices for offline-first mobile apps

Please help me with a starting point to available patterns and practices for building reliable offline-first mobile apps. Offline-first means that:

1. app is client-server


2. a mobile app is able to function without Internet connection. User can CRUD data.


3. once user enters in Internet enabled area - app synchronises with the server.


4. user uses the app on multiple devices so that there should be kind of synchronisation mechanism supporting versioning. The simplest one.

Thanks!