swiftui-development

SwiftUI Development

Declarative composition, predictable state and safe concurrency. Prefer small views and testable ViewModels when the project uses MVVM. Language: swift. Persistence: swiftdata. IAP: storekit. Widgets: widgetkit. Visual style: better-mobile-interface. i18n: i18n-mobile. Mac platform: macos-development. Watch: watchos-development. iOS deploy: github-actions-ios.

Composition

• Small views, named by purpose.
• Extract subviews and ViewModifiers instead of giant bodies.
• Prefer composition over inheritance.
• Layout containers (VStack, Grid, Layout) with spacing from the app's design system.
• Tests: swift-testing (Swift Testing + XCUITest).

State

• @State — local view state.
• @Binding — borrowed state.
• @Observable / Observation — modern models and ViewModels.
• @Environment — cross-cutting dependencies (not for every feature state).
• Avoid legacy @ObservedObject in new code if Observation is available in the deployment target.

Rules:

• Single source of truth.
• Side effects in .task / .onChange with cooperative cancellation.
• Do not do networking in body.

Navigation

• NavigationStack with typed value (navigationDestination).
• Sheets/fullScreenCover with stable identity.
• Deep links: parse → route state → stack.
• Avoid legacy NavigationView in new code.

Concurrency

• async/await and Task with cancellation in .task.
• @MainActor for UI state.
• Do not block the main thread with I/O.
• Model errors with throws and failure states in the UI.

Architecture

• If the app uses MVVM, apply the skill mvvm-architecture.
• Injectable services/repositories for testing.
• Separate networking from the View.

Accessibility and UI polish

• Labels, traits, Dynamic Type.
• Touch targets and contrast.
• Reduce motion when accessibilityReduceMotion.
• SF Symbols with coherent typographic hierarchy.

Previews and performance

• Previews with sample data and states (loading/error/empty).
• Avoid heavy work in body; use EquatableView / conscious diffing when needed.
• Large lists: List/LazyVStack appropriate; identify with stable id .
• Profile with Instruments if there is jank.

Tests

• ViewModels/services with XCTest.
• UI tests for critical flows.
• Snapshots only if the project already depends on them.

Anti-patterns

• Massive ContentView
• Networking and parsing in body
• @State for server data without a model layer
• Force unwrap in production paths
• Ignoring task cancellation

Completion criteria

• Correct state and concurrency on the MainActor
• Stable typed navigation
• Previews of the main states
• Basic A11y covered
• No unnecessary force unwraps on the happy path/handled error