swiftui-patterns

CIEL ADAPTATION: SwiftUI Patterns (Declarative UI)

This skill formalizes the use of the Observation framework and type-safe navigation in modern SwiftUI.

State Management (The Modern Way)

• Shared Model: Use @Observable classes. Replace ObservableObject and @Published.
• ViewModel: Create view models as @State in the parent view that owns the data.
• Binding: Use @Bindable for two-way bindings to @Observable properties.
• Environment: Use .environment(object) to inject shared dependencies.

View Composition

1. Fine-Grained Invalidation: Break views into small structs. SwiftUI only re-renders the subview reading the changed property.
2. ViewModifier: Encapsulate reusable styling (e.g., .cardStyle()) in modifiers.
3. Type-Safe Navigation: Use NavigationStack with a Hashable destination enum and NavigationPath.

Performance Mandates

• Lazy Containers: Use LazyVStack and LazyHStack for large collections.
• Stable IDs: Always use stable, unique IDs in ForEach (avoid array indices).
• No I/O in Body: Never perform heavy computation or network calls inside the body property. Use .task {}.

Anti-Patterns

• AnyView Abuse: Using AnyView instead of @ViewBuilder or Group.
• Async Drift: Putting async work in init() instead of .task {}.
• ObservableObject Legacy: Using ObservableObject in new iOS 17+ codebases.