Mobile Engineering Agents

Appearance

Standard: SwiftUI Standards ​

Rules for SwiftUI UI code. Complements coding_standards.md. Enforced in review by the SwiftUI Expert and Accessibility Expert.

Views ​

  • The View is a function of state — no networking, persistence, or business logic in body.
  • Extract a subview when body exceeds ~40 lines or repeats.
  • One primary View per file plus its tightly-coupled subviews.
  • Side effects via .task {}/.onChange, delegated to the ViewModel.
swift
// ✅ thin view bound to state
var body: some View {
    switch viewModel.state {
    case .loading: ProgressView()
    case .loaded(let items): List(items) { ItemRow($0) }
    case .failed(let msg): ErrorView(message: msg) { Task { await viewModel.load() } }
    case .idle: Color.clear.task { await viewModel.load() }
    }
}

State Management ​

  • One source of truth per piece of state; don't duplicate model data into local @State.
  • New code uses Observation (@Observable ViewModels, @State to own them).
  • @State for view-local value state; @Binding for two-way child state; @Environment for dependency/context.
  • Model screen state as a single enum (idle/loading/loaded/failed), not scattered booleans.
  • ViewModels are @MainActor.
  • Use NavigationStack with value-based destinations (navigationDestination(for:)).
  • Centralize routing (router/coordinator); don't scatter navigation booleans across views.

Styling ​

  • Use semantic colors and Font text styles; no hardcoded font sizes (Dynamic Type).
  • Centralize design tokens (spacing, colors, typography) in a design system.
  • Support light/dark mode; verify both.

Performance ​

  • LazyVStack/List for large collections; stable id in ForEach.
  • Keep expensive work out of body; memoize derived values.
  • Avoid unnecessary AnyView; prefer @ViewBuilder.

Accessibility (required, not optional) ​

  • Every interactive element has a label + correct trait.
  • Layout survives the largest Dynamic Type size.
  • Color is never the only signal; touch targets ≥ 44×44 pt.
  • Add accessibility identifiers for UI testing. (Full gate: checklists/accessibility_review.md.)

Previews ​

  • Provide previews with injected stub dependencies and multiple states (loading/error/loaded), plus a large-Dynamic-Type variant for key screens.