SwiftUI architecture patterns, state management with @Observable, view composition, navigation, performance optimization, and modern iOS/macOS UI best practices. Use when building or reviewing SwiftUI views, @Observable state, navigation, or render performance.

SwiftUI Patterns Modern SwiftUI patterns for building declarative, performant user interfaces on Apple platforms. Covers the Observation framework, view composition, type safe navigation, and performance optimization. When to Activate Building SwiftUI views and managing state ( @State , @Observable , @Binding ) Designing navigation flows with NavigationStack Structuring view models and data flow Optimizing rendering performance for lists and complex layouts Working with environment values and dependency injection in SwiftUI State Management Property Wrapper Selection Choose the simplest wrapper that fits: Wrapper Use Case @State View local value types (toggles, form fields, sheet presentation) @Binding Two way reference to parent's @State @Observable class + @State Owned model with multiple properties @Observable class (no wrapper) Read only reference passed from parent @Bindable Two way binding to an @Observable property @Environment Shared dependencies injected via .environment() @Observable ViewModel Use @Observable (not ObservableObject ) — it tracks property level changes so SwiftUI only re renders views that read the changed property: View Consuming the ViewModel Environment Injection Replace @EnvironmentObject with @Environment : View Composition Extract Subviews to Limit Invalidation Break views into small, focused structs. When state changes, only the subview reading that state re renders: ViewModifier for Reusable Styling Navigation Type Safe NavigationStack Use NavigationStack with NavigationPath for programmatic, type safe routing: Performance Use Lazy Containers for Large Collections LazyVStack and LazyHStack create views only when visible: Stable Identifiers Always use stable, unique IDs in ForEach — avoid using array indices: Avoid Expensive Work in body Never perform I/O, network calls, or heavy computation inside body Use .task {} for async work — it cancels automatically when the view disappears Use .sensoryFeedback() and .geometryGroup() sparingly in scroll views Minimize .shadow() , .blur() , and .mask() in lists — they trigger offscreen rendering Equatable Conformance For views with expensive bodies, conform to Equatable to skip unnecessary re renders: Previews Use Preview macro with inline mock data for fast iteration: Anti Patterns to Avoid Using ObservableObject / @Published / @StateObject / @EnvironmentObject in new code — migrate to @Observable Putting async work directly in body or init — use .task {} or explicit load methods Creating view models as @State inside child views that don't own the data — pass from parent instead Using AnyView type erasure — prefer @ViewBuilder or Group for conditional views Ignoring Sendable requirements when passing data to/from actors References See skill: swift actor persistence for actor based persistence patterns. See skill: swift protocol di testing for protocol based DI and testing with Swift Testing.

swiftui-patterns