Setting Up TCA for iOS: SwiftUI + Composable Architecture

Synchronizing state across multiple screens and complex navigation in a SwiftUI app often leads to hard-to-find bugs. You spend hours debugging, and changes in one module break others. The Composable Architecture (TCA) from Point-Free — The Composable Architecture — enforces a strict unidirectional data flow with deterministic testing. We integrate TCA into SwiftUI projects with iOS 17+ and Swift 5.9, configure reducer composition, and handle dependency injection via DependencyValues. The result: predictable code that you can test without a simulator.

Our turnkey TCA setup includes analyzing your current architecture, installing via SPM, and training your team. Contact us for a project assessment—we'll show how TCA fits your specific app.

How TCA Solves Global State Problems

TCA from Point-Free is not just another folder structure in Xcode. It's a strict unidirectional data flow where the entire app state mutates only through a Reducer, and every change is tested deterministically. If you work with SwiftUI, complex navigation, and a large team, TCA provides tools that MVVM lacks.

Store, State, Action, Reducer, Effect — these are the five pillars of TCA.

State is a structure describing everything a screen needs. Action is an enum with associated values describing everything that can happen. Reducer is a pure function (State, Action) -> Effect<Action>. Effect is a wrapper for async work (network, timers, MotionManager).

@Reducer struct ProfileFeature { @ObservableState struct State: Equatable { var user: UserProfile? var isLoading = false var errorMessage: String? } enum Action { case loadProfile(id: String) case profileLoaded(Result<UserProfile, Error>) case editButtonTapped } @Dependency(\.userClient) var userClient var body: some Reducer<State, Action> { Reduce { state, action in switch action { case let .loadProfile(id): state.isLoading = true return .run { send in await send(.profileLoaded( Result { try await userClient.fetch(id) } )) } case let .profileLoaded(.success(user)): state.isLoading = false state.user = user return .none case let .profileLoaded(.failure(error)): state.isLoading = false state.errorMessage = error.localizedDescription return .none case .editButtonTapped: return .none } } } } 

The view contains no logic: store.send(.loadProfile(id: userId)) and store.user — all interaction through the Store.

TCA vs MVVM Comparison

The table simplifies the choice: TCA pays off with teams of 3+ and a requirement of >80% test coverage.

How to Test TCA Reducers

TCA provides TestStore, which verifies every state change in response to an action. If the state changes in an unexpected way, the test fails. This eliminates false positives and guarantees that state regressions are impossible. With this approach, business logic test coverage reaches 80–90%.

func test_loadProfile_success() async { let store = TestStore(initialState: ProfileFeature.State()) { ProfileFeature() } withDependencies: { $0.userClient.fetch = { _ in .stub(id: "42") } } await store.send(.loadProfile(id: "42")) { $0.isLoading = true } await store.receive(.profileLoaded(.success(.stub(id: "42")))) { $0.isLoading = false $0.user = .stub(id: "42") } } 

TestStore requires you to explicitly describe every state change. If something changes but is not described, the test fails. Writing these tests is costly, but they completely eliminate state regressions and cut regression testing time by 40%.

Why TCA Over Singletons for Dependencies

Singletons like URLSession.shared make code brittle for testing. TCA replaces them with DependencyValues — explicit dependency declarations that can be swapped. In tests: withDependencies { $0.userClient = .mock } { ... }. No stub protocols, no setUp/tearDown with global state.

extension DependencyValues { var userClient: UserClient { get { self[UserClientKey.self] } set { self[UserClientKey.self] = newValue } } } 

Steps for Setting Up TCA

1. Analyze current architecture and identify modules (1–2 days)
2. Install TCA via Swift Package Manager (latest version)
3. Build a sample Reducer with TestStore coverage
4. Integrate DependencyValues for network layer, data storage, etc.
5. Migrate 3–5 screens as a demo for the team
6. Training: 2–3 live code review sessions
7. Document coding standards and conventions

Process: Timelines and Results

Timelines and Cost

Setting up TCA from scratch takes 5 to 8 days. Migrating an existing project takes 3 to 6 weeks. Cost is calculated individually after assessing scope and current architecture. We have experience with over 50 projects on TCA — from social networks to fintech. We guarantee architecture stability and full testability.

Request TCA setup for your project. Get a consultation from our engineers — we'll assess complexity and timelines. Contact us through the form on our website.