IOS Swift UI

When to activate

• Building iOS apps with SwiftUI
• Implementing async data loading with Swift Concurrency
• Persisting data with SwiftData or Core Data
• Integrating Apple frameworks (HealthKit, MapKit, WidgetKit)
• Preparing apps for App Store submission

When NOT to use

• For cross-platform apps (use react-native-expo or flutter-widgets)
• For Android-only development
• For macOS-only apps (different framework)

Instructions

1. Project structure. MVVM: Views (SwiftUI) → ViewModels (@Observable) → Services (async/await) → Models (SwiftData).
2. SwiftUI views. Keep views small and composable. Use @State for local, @Bindable for shared, @Environment for injected.
3. Async data. async let for parallel, Task for background work, .task modifier for view lifecycle. Handle loading/error states explicitly.
4. SwiftData. @Model for entities, @Query for fetching, ModelContainer for setup. Migrate from Core Data only if benefits outweigh effort.
5. Navigation. NavigationStack with type-safe NavigationPath. Define routes as enums. Support deep linking via onOpenURL.
6. Accessibility. .accessibilityLabel, .accessibilityHint, Dynamic Type support with @ScaledMetric, VoiceOver testing.
7. Testing. XCTest for unit, XCUITest for UI, Snapshot tests for visual regression.

Example

@Observable
class ProductListViewModel {
    var products: [Product] = []
    var isLoading = false
    var error: Error?

    func loadProducts() async {
        isLoading = true
        defer { isLoading = false }
        do {
            products = try await api.fetchProducts()
        } catch {
            self.error = error
        }
    }
}

struct ProductListView: View {
    @State private var viewModel = ProductListViewModel()

    var body: some View {
        NavigationStack {
            List(viewModel.products) { product in
                NavigationLink(value: product) {
                    ProductRow(product: product)
                }
            }
            .task { await viewModel.loadProducts() }
        }
    }
}