Offline Strategies In React Native

Nwolisa argues that reliable connectivity is an unsafe assumption: users move between fast networks and no connection. She cites a figure that about 45% of connected devices have speeds at or below 2 Mbps, and demonstrates that downloading a 14 MB file at that speed takes about 43 seconds.

Offline apps need local persistence, but deciding when cached data is stale is the harder problem. Nwolisa suggests using timestamps and overwriting cached data rather than deleting it, so users can see stale information instead of nothing. Her repository pattern checks memory, then disk, then network, saving network results to disk and memory for later use.

Clear connection messages help users understand what is available offline; Nwolisa points to Gmail, Coursera, and YouTube as examples and mentions React Native NetInfo for detecting connection changes. Read intensive apps mainly display data, while write intensive apps also need a way to preserve and sync user-created changes. She describes CouchDB replication and, for existing systems, a change log with incremental sync and exponential backoff for failures.

Nwolisa describes a radio app that let users download recorded shows after they reported slow playback and breaks in recordings. Downloads made listening smoother and available offline. She also recommends image caching, including React Native Fast Image, which wraps Glide on Android and SDWebImage on iOS.

Nwolisa closes with three principles: communicate clearly, use local data where possible, and offer downloads. She emphasizes that the right offline experience depends on the app and its users, based on her work building three offline applications.