Designing for offline from the start
Offline capability is hard to bolt on later because it changes how data flows through the whole app. The apps that handle it well treat the device as the source of truth for the moment: they read and write locally first, then sync with the server in the background when a connection is available.
That local store can be Core Data, SwiftData, SQLite, or a lightweight file cache depending on the app. The right choice depends on how much data you hold, how it's queried, and how it needs to sync.
- A local database (Core Data, SwiftData, or SQLite) as the on-device source of truth
- Reading and writing locally so the UI never waits on the network
- Queuing changes made offline for later sync
- Caching images and content for use without a signal
- Clear UI states that tell users what's saved, pending, or synced
Syncing and resolving conflicts
The hard part of offline apps isn't storing data — it's reconciling it. When a user changes something offline and the server or another device also changed it, the app needs a defined rule for what wins. Ignoring that leads to silent data loss, which is worse than an error.
We design the sync and conflict strategy up front: what merges, what the user is asked about, and how failed syncs retry. For apps that fit its model, CloudKit can handle a lot of this; for others, we build sync against your own backend.
- Background sync that retries safely when connectivity returns
- A defined conflict-resolution rule (last-write-wins, merge, or prompt the user)
- Protection against duplicate or lost records during sync
- CloudKit for apps that fit Apple's sync model
- Custom sync against your API when you need more control
- Handling of partial syncs, timeouts, and interrupted connections
More on ios apps
Frequently asked questions
Can any app be made to work fully offline?
Most of an app can, but not always all of it. Features that fundamentally need the network — live prices, real-time chat, fresh search results — can't run offline, though they can degrade gracefully and cache their last state. We help you decide which parts must work offline and design around that honestly.
What's the hardest part of building an offline app?
Sync conflicts. Storing data locally is straightforward; deciding what happens when the same record changes in two places while offline is where apps get it wrong and lose data. Getting that rule right for your app deserves the most attention, and we design it deliberately rather than hoping it won't come up.
Should I use CloudKit or a custom backend for sync?
CloudKit is a strong fit if your data is per-user and you're all-in on Apple's ecosystem, and it's cost-effective. A custom backend makes sense when you need cross-platform access, complex server logic, or more control over the data. We'll recommend based on your app in a free consultation.