Example: Social Media App

A reference architecture for a feed-centric social app. Demonstrates an infinite feed, media handling, and realtime interactions at scale.

What it demonstrates

• Clean Architecture + MVVM across Feed, Post, Profile, and Notifications features.
• Infinite-scroll feed with cursor pagination and prefetching.
• Efficient image/video handling (downsampling, bounded caches).
• Realtime likes/comments via WebSocket or SSE; push notifications with deep links.

Module Map

Feed: Pagination + Performance

• Cursor pagination, de-dup by post id, prefetch a few items before the end (skills/networking/ios/pagination.md).
• LazyVStack/List with stable ids; images downsampled to cell size; bounded MediaCache (skills/performance/ios/memory_optimization.md).

.onAppear { Task { await viewModel.loadNextPageIfNeeded(currentItem: post) } }

Realtime Interactions

• Live like/comment counts via SSE (server→client) or a WebSocket (skills/networking/ios/sse.md); counts coalesce so a hot post doesn't flood the UI.

Authentication

• OAuth2 + PKCE; the feed personalizes per session; tokens in Keychain.

Dependency Injection

• Composition root wires feed/post/profile repositories, realtime streams, and MediaCache.

Error Handling

• Feed load failures show a retry state; a single failing post never breaks the list.
• Optimistic like with rollback on server failure.

Testing Strategy

• Unit: pagination/de-dup, optimistic like/rollback, feed view-model states.
• Integration: feed decode + realtime count updates with a fake stream.
• UI: scroll feed + like a post happy path.

Scalability Considerations

• Handles very large feeds via pagination, lazy loading, and image downsampling.
• Backpressure on realtime counters (coalesce to latest).
• Battery: prefer push/SSE over polling; respect Low Power Mode (skills/performance/ios/battery_optimization.md).

Build it with the toolkit

workflows/create_feature.md → workflows/integrate_websocket.md → workflows/optimize_performance.md.