iOS State Management Skill

Agent Skills: iOS State Management

Manage reactive state with Combine, Observation framework, and UDF patterns. Use when implementing state management with Combine, @Observable, or reactive patterns in iOS. (triggers: **/*.swift, Observable, @Published, PassthroughSubject, @Observable, @Namespace)

UncategorizedID: hoangnguyen0403/agent-skills-standard/ios-state-management

iOS State Management

Priority: P0

Implementation Workflow

Choose observation approach — Use @Observable (iOS 17+) for modern SwiftUI; Combine with @Published for UIKit or broader compatibility.
Expose state clearly — Use UDF pattern: ViewModel exposes Input enum (events) and Output struct (state).
Manage subscriptions — Store Combine subscriptions in Set<AnyCancellable> with .store(in: &cancellables).
Dispatch to main thread — Use @MainActor or .receive(on: DispatchQueue.main) for UI updates.
Use exhaustive ViewState — Prefer a single ViewState enum (.loading, .success(data), .error(failure)).

See Combine and Observation framework examples

Anti-Patterns

❌ Uncleared subscriptions — always use .store(in: &cancellables)
❌ UI updates on background thread — use .receive(on: .main) or @MainActor
❌ Manual objectWillChange.send() — use @Published or @Observable instead

References

Combine & Observation Setup