Setting Up MVI Architecture for Android App

Setting Up MVI Architecture for Android App

We, the Android development team, often encounter projects where MVVM with mutable LiveData no longer suffices. Imagine: a user simultaneously pulls a list to refresh, presses a button, and receives a push notification — three events that can be processed in unpredictable order. In a real MVVM project we saw a race condition with a 30% probability when repeating the scenario. MVI solves this problem fundamentally.

MVI (Model-View-Intent) is a paradigm shift: instead of two-way data bindings, you get a unidirectional flow where the UI state is predictable at any point in time. Over 30+ completed projects, we have confirmed: MVI reduces time spent debugging race conditions by 2 times compared to classic MVVM, and test coverage reaches 90%.

Why MVI Is Better Than MVVM for Complex Screens

Single source of truth — UiState. The entire screen is described by one immutable structure. No isLoading = true in one place and showError() in another — there is UiState.Loading, UiState.Success(data), UiState.Error(message). The current screen state is always a single object. This guarantees reproducibility: knowing the initial state and the sequence of Intents, the result can be precisely predicted. Our measurements show: the frequency of state-related bugs drops by 70% after migrating to MVI.

Intent is not an Android Intent. In MVI it's a user action: RefreshIntent, SearchIntent(query), LoadMoreIntent. The ViewModel accepts a stream of Intents and transforms them into states via reduce. At the same time, all side-effects (navigation, toasts) are moved to a separate channel — Effect.

How to Implement MVI in Kotlin + Coroutines

Here is a typical contract for a profile screen:

data class ProfileUiState(
    val isLoading: Boolean = false,
    val profile: UserProfile? = null,
    val error: String? = null,
    val isRefreshing: Boolean = false
)

sealed class ProfileIntent {
    data class Load(val userId: String) : ProfileIntent()
    object Refresh : ProfileIntent()
    data class Follow(val targetId: String) : ProfileIntent()
}

sealed class ProfileEffect {
    data class NavigateToEdit(val userId: String) : ProfileEffect()
    data class ShowSnackbar(val message: String) : ProfileEffect()
}

The ViewModel manages state via StateFlow:

@HiltViewModel
class ProfileViewModel @Inject constructor(
    private val getProfile: GetUserProfileUseCase,
    private val followUser: FollowUserUseCase
) : ViewModel() {

    private val _state = MutableStateFlow(ProfileUiState())
    val state: StateFlow<ProfileUiState> = _state.asStateFlow()

    private val _effects = Channel<ProfileEffect>(Channel.BUFFERED)
    val effects: Flow<ProfileEffect> = _effects.receiveAsFlow()

    fun processIntent(intent: ProfileIntent) {
        when (intent) {
            is ProfileIntent.Load -> loadProfile(intent.userId)
            is ProfileIntent.Refresh -> refreshProfile()
            is ProfileIntent.Follow -> followUser(intent.targetId)
        }
    }

    private fun loadProfile(userId: String) {
        viewModelScope.launch {
            _state.update { it.copy(isLoading = true, error = null) }
            getProfile(userId).fold(
                onSuccess = { profile ->
                    _state.update { it.copy(isLoading = false, profile = profile) }
                },
                onFailure = { e ->
                    _state.update { it.copy(isLoading = false, error = e.message) }
                    _effects.send(ProfileEffect.ShowSnackbar(e.message ?: "Unknown error"))
                }
            )
        }
    }
}

In Jetpack Compose, consuming the state looks like:

val state by viewModel.state.collectAsStateWithLifecycle()

LaunchedEffect(userId) {
    viewModel.processIntent(ProfileIntent.Load(userId))
}

A button sends viewModel.processIntent(ProfileIntent.Follow(targetId)) — no direct UI mutation.

For side-effects (navigation, toasts), use Channel or SharedFlow. In Fragment/Activity, subscribe via lifecycleScope.launch { viewModel.effects.collect { ... } }.

Comparison of MVI and MVVM: When to Choose What

Conclusion: for simple CRUD screens, MVVM is enough. MVI is justified when there are multiple event sources, complex UI states with flags, or high testability requirements — for example, order screens, chat, real-time monitoring.

How to Simplify MVI with Orbit MVI

Writing MVI from scratch for every project is excessive. Orbit MVI is a library from the Mobile Native Foundation that offers a concise DSL:

class ProfileViewModel : ContainerHost<ProfileUiState, ProfileEffect>, ViewModel() {
    override val container = container<ProfileUiState, ProfileEffect>(ProfileUiState())

    fun load(userId: String) = intent {
        reduce { state.copy(isLoading = true) }
        val profile = getProfile(userId).getOrThrow()
        reduce { state.copy(isLoading = false, profile = profile) }
    }
}

orbit-mvi is compatible with Hilt and provides convenient test blocks test { } from orbit-testing. This speeds up development and reduces boilerplate by 30%.

Typical Mistakes When Implementing MVI

• UiState too large: split into substates or use sealed class for different modes.
• Side-effects via State: use Channel for one-shot events, not StateFlow.
• No tests for coroutines: use turbine and kotlinx-coroutines-test.
• Overcomplicating simple screens: MVI is not needed for a single input field.

What Is Included in Turnkey MVI Setup

We offer:

• Choice of approach: manual implementation or Orbit MVI.
• Setting up a base contract (UiState, Intent, Effect).
• Implementation of an example module with tests via turbine + kotlinx-coroutines-test.
• Documentation for the team with examples of handling edge cases.

Contact us for an assessment of your project — we will calculate timelines and cost individually. Get a consultation on migrating your app to MVI today.

Work Stages

Timelines and How We Work

• Setting up MVI from scratch (structure + first module with tests): 3–5 days.
• Migrating an MVVM project to MVI: 2–4 weeks.
• All projects include code review and test coverage.

Order MVI setup for your Android app — get a predictable architecture that is easy to test and maintain.

Mobile App Architecture

The app is built in a single ViewController with 2000 lines. Network calls, business logic, UI updates—all in one place. Adding a new feature without regression is difficult, writing a test is impossible. This isn’t “bad code”—it’s a lack of architecture. And it’s more common than you might expect, even in production apps with millions of users.

We design architecture turnkey: from pattern selection to complete project structure with tests and documentation. In 7–10 days you get clean, modular code ready for scaling.

Architecture patterns in mobile solve one problem: separate UI from logic so each part is testable and replaceable.

MVVM: Basic Pattern

Model-View-ViewModel is the standard for iOS (SwiftUI + Combine/async, UIKit + Combine) and Android (Jetpack ViewModel + StateFlow + Compose). The ViewModel holds UI state and business logic. The View only displays state and forwards user intentions to the ViewModel. The Model represents data and its source.

Key rule: ViewModel knows nothing about UIKit or Android View classes. No UIKit imports, no Context dependencies (except Application context through Hilt). This ensures testability: ViewModel is tested as pure Kotlin/Swift code without Android Instrumented Test.

MVVM covers 70% of needs. The remaining 30% require strict feature isolation, team scaling, or complex state management flows.

Clean Architecture: When MVVM Isn’t Enough

Adds layers on top of MVVM:

• Domain layer — business logic, platform-independent. A UseCase (or Interactor) contains a single business rule: GetUserOrdersUseCase, PlaceOrderUseCase. Depends only on interfaces (protocol/interface), not concrete implementations.
• Data layer — repository implementations. OrderRepositoryImpl implements OrderRepository from domain. Knows about Retrofit, Room, UserDefaults. The ViewModel doesn’t know where data comes from—network or cache.
• Presentation layer — ViewModel + View. Knows about Domain, not Data.

Dependency rule: dependencies point inward only. Domain depends on nothing. Data and Presentation depend on Domain.

Presentation → Domain ← Data

This allows swapping implementations: tests use an in-memory repository instead of network, the interface remains the same.

Practical caveat: Clean Architecture adds files and layers. For small apps, this is overhead. It’s justified starting from ~15 features and teams of 3+ developers.

BLoC for Flutter: Predictable State Flow

BLoC (Business Logic Component) is the standard pattern in the Flutter community. The flutter_bloc library implements it with two types: Bloc (Event → State) and Cubit (State without Events, only methods).

Bloc processes Event and emits a new State via on<EventType> handlers. State is immutable—a new object for each change. BlocBuilder re-renders only the part of the tree where state changed.

// Event
abstract class CartEvent {}
class AddItemToCart extends CartEvent {
  final String productId;
  AddItemToCart(this.productId);
}

// State
abstract class CartState {}
class CartLoaded extends CartState {
  final List<CartItem> items;
  CartLoaded(this.items);
}

// Bloc
class CartBloc extends Bloc<CartEvent, CartState> {
  CartBloc(this._cartRepository) : super(CartLoaded([])) {
    on<AddItemToCart>(_onAddItem);
  }

  Future<void> _onAddItem(AddItemToCart event, Emitter<CartState> emit) async {
    final current = state as CartLoaded;
    final updated = await _cartRepository.addItem(event.productId);
    emit(CartLoaded(updated));
  }
}

The advantage of BLoC is testability. blocTest from the bloc_test package allows you to verify: given a certain Event and initial State, the BLoC should emit a certain State. No UI, no mocks for the Flutter framework.

VIPER: For Large iOS Projects

VIPER (View, Interactor, Presenter, Entity, Router) is the strictest separation of responsibilities for iOS. Each component has a protocol and concrete implementation.

• View — UI only, delegates everything to Presenter
• Interactor — business logic, network and data operations
• Presenter — mediator between View and Interactor, formats data for View
• Entity — data models (pure structures)
• Router — navigation between modules

Each module (screen or feature) is a separate VIPER module. This eliminates coupling between features and allows large teams to work in parallel without conflicts.

The cost: many files, many protocols. Boilerplate is generated via Sourcery or custom Xcode templates. VIPER is justified for apps with 10+ developers and 50+ screens.

TCA (The Composable Architecture)

TCA by Point-Free is a more modern alternative to VIPER for iOS/macOS. Core concepts: State (immutable feature state), Action (all possible events), Reducer (State + Action → new State + Effect), Store (holds State, processes Actions).

Scope allows composable building of large features from small ones: a parent Reducer delegates part of State to a child. Each feature is tested in isolation via TestStore with precise control over Effects.

TCA has a steep learning curve but provides predictability that is hard to achieve otherwise: every state change is an explicit Action with a specific source.

Which Pattern to Choose for Your Project?

We’ll evaluate your project in 1 day—choose an architecture considering team size, platform, and growth plans.

There is no universal answer. Architecture is chosen based on team size, testability requirements, and app support horizon.

What Components Are Included in Our Architecture Work?

• Audit of current architecture (if the app already exists)—identify bottlenecks and regression areas.
• Design of modular structure with clear layer boundaries and dependency rules.
• Creation of project scaffold with DI setup, folder organization, and linter configuration.
• Writing unit tests for domain layer and ViewModel—minimum 80% coverage of key use cases.
• Preparation of documentation—architecture diagrams, README with code modification rules, onboarding guide for new developers.
• Delivery of a working repository with CI pipeline (GitHub Actions / Bitrise) configured to run tests and static analysis.

All this is included in the design cost. Additionally, support during implementation: team consultations, code review of first pull requests.

How Does Lack of Architecture Affect Development Speed?

Typical scenario after 18 months without architecture: 40% of development time goes to debugging regressions. A new developer spends a week understanding the code before making their first PR. Tests aren’t written “because it’s hard to mock.” Adding a new feature requires understanding half the codebase.

Choosing architecture at the start is an investment that pays off in 3–6 months. According to our data, a properly designed architecture with MVVM + Clean gives 3x fewer regressions compared to a monolithic ViewController. And the cost of implementation is recouped in 2–3 sprints.

According to Apple’s recommendations, separation of responsibilities is a key factor in code stability.

Why Trust Our Team with Architecture?

An incorrect pattern choice at the start leads to rewriting half the code a year later. We’ve seen dozens of projects where trying to save on architecture resulted in months of refactoring. With over 10 years of commercial development experience and work on apps from 1 to 50 developers, we help avoid common mistakes:

• Overengineering for a simple MVP (we assign MVVM, not VIPER).
• Lack of dependency injection—we integrate Hilt/Koin/Dagger from the start.
• Ignoring testability—we establish protocols/interfaces from the first commit.

We’ve architected over 200 mobile applications for startups and enterprises, with guaranteed 80%+ test coverage and CI/CD pipelines. Our team holds certifications in iOS and Android development, and we follow the App Store Review Guidelines (Section 4.2/5.1) to ensure smooth store approvals.

Start with a free architecture audit — send us your project description and we’ll deliver a tailored architecture plan within 24 hours. Reach out via Telegram or email to get started.