swiftui-ui-patterns

Choose based on ownership: use @State for local view state, @State with an @Observable type for root-owned reference models on iOS 17+, and @Environment for shared app services. Pick the ownership location first, then select the narrowest wrapper that fits.

Create one NavigationStack per tab, each bound to its own router object holding a path array of Hashable route enums. Inject the router via the environment so child views navigate programmatically, and centralize destination mapping with navigationDestination(for:).

Prefer sheet(item:) when the state represents a selected model, as it guarantees a single active sheet and avoids if-let unwrapping inside the sheet body. For app-wide modals, centralize presentation with an enum-driven SheetDestination stored on a router.

No, the Observation framework requires iOS 17 or later. For iOS 16 and earlier, fall back to ObservableObject with @StateObject for root ownership, @ObservedObject for injected objects, and @EnvironmentObject only for truly shared app-level state.

Excessive re-renders usually come from unstable ForEach identity, expensive computation inside body, or overly broad observation scope. Give rows stable IDs, move heavy transforms into models, and narrow observation so only views reading changed state update.

Use .task for load-on-appear work and .task(id:) when work should restart for changing inputs like search queries. Treat cancellation as normal, debounce user-driven requests, and keep explicit loading, loaded, and error states.