Offline mode is no longer just an extra feature you could choose to add to your app — it’s something many users expect. I’ve often seen developers force their favorite offline solution on a problem…
— Read on medium.com/device-blogs/the-many-offline-options-for-ios-apps-2922c9b3bff3

Summary

Runs through Caches vs. Databases and when each is a better fit. Basically, databases are better for a finite set of data that you can save “all” of, perhaps a game of personal database. Caches are better for something that is too big / complex / dynamic to save “all” of, e.g. social media, web, etc.

Also covers the idea of using a queue (or EveneBus) for offline tasks and mixing strategies.