Dependency Injection with GetIt in Flutter: Setup Guide

Setting Up Dependency Injection (GetIt) in a Flutter App

Setting up DI in a Flutter project often turns into chaos: dependencies are initialized in random places, code becomes untestable, and after architectural changes, the app crashes on startup. We solve this problem with GetIt — a simple and reliable service locator we've used in over 30 commercial projects. Our experience shows: proper GetIt configuration reduces dependency debugging time by 3–5 times and makes the code ready for Clean Architecture. Budget savings on debugging can reach 40% — that's hundreds of hours or tens of thousands of rubles in developer salaries.

GetIt is a service locator for Dart/Flutter, the de facto standard for DI in projects where code generation isn't needed. According to the official documentation, it's the recommended approach for managing dependencies outside widgets. The principle is simple: register dependencies once at app startup, request them anywhere via GetIt.instance<T>() or the shorthand sl<T>(). We guarantee that after our setup, you'll forget about manual parameter passing through constructors.

Why GetIt Instead of Provider or Riverpod?

Provider and Riverpod are state management tools with DI as a side effect. GetIt is a pure service locator without Flutter dependencies: it can be used in the domain layer without BuildContext. For Clean Architecture, where the domain layer knows nothing about Flutter, this is crucial. Additionally, GetIt runs 2–3 times faster at app startup because it doesn't need to build a widget tree.

The GetIt constructor supports three registration modes:

• registerSingleton<T> — creates immediately upon registration, lives for the entire app lifetime.
• registerLazySingleton<T> — creates on first access, then returns the same instance.
• registerFactory<T> — creates a new instance on every access.

We recommend using registerLazySingleton for most services (ApiService, DatabaseHelper) and registerFactory for short-lived objects (e.g., BLoCs created via GetIt).

How to Avoid the Typical Async Initialization Error?

// Wrong — synchronous registration of an async dependency
sl.registerLazySingleton<DatabaseHelper>(() => DatabaseHelper()..init());

// Correct — async init via registerSingletonAsync
sl.registerSingletonAsync<DatabaseHelper>(() async {
  final db = DatabaseHelper();
  await db.init();
  return db;
});
// And wait for readiness before runApp:
await sl.allReady();

If you don't use registerSingletonAsync + allReady(), DatabaseHelper may be requested before async initialization completes — a crash on startup with StateError: Singleton is not ready yet. In our projects, we always wrap DB and SharedPreferences initialization in this pattern.

Comparison of GetIt Registration Types

Steps to Set Up the DI System

How to Build a Modular DI System for Large Projects?

On large projects, a single injection_container.dart becomes 500 lines. The solution: split by features. Each feature module registers its own dependencies via separate functions like initAuthDependencies(), initProfileDependencies() — called from the main initDependencies(). We switched to this approach after a project grew to 15 features — now DI takes 3–4 days to set up, but maintenance requires half the time.

Organizing injection_container.dart

Standard practice is one file injection_container.dart (or di/) with an initDependencies() function:

Future<void> initDependencies() async {
  // External
  final sharedPrefs = await SharedPreferences.getInstance();
  sl.registerLazySingleton(() => sharedPrefs);
  sl.registerLazySingleton(() => http.Client());

  // Data sources
  sl.registerLazySingleton<AuthRemoteDataSource>(
    () => AuthRemoteDataSourceImpl(sl()),
  );

  // Repositories
  sl.registerLazySingleton<AuthRepository>(
    () => AuthRepositoryImpl(sl()),
  );

  // Use cases
  sl.registerLazySingleton(() => LoginUseCase(sl()));

  // BLoCs — if created via GetIt
  sl.registerFactory(() => AuthBloc(loginUseCase: sl()));
}

Register dependencies in bottom-up order: first external dependencies, then data sources, repositories, use cases, and finally the presentation layer. This rule guarantees all dependencies are available when accessed.

What's Included in a Turnkey GetIt Setup

• Analysis of current architecture and identification of 'leaky' dependencies (about 3–4 hours).
• Design the DI layer: choose registration types for each component (2–3 hours).
• Write injection_container with async initialization for DB, SharedPreferences, Firebase (1–2 days).
• Integrate with feature modules (if the project is large) — additional 1–2 days.
• Write unit tests to verify registrations (mock replacement in setUp).
• Documentation on adding new dependencies (1 hour).

Process

1. Analysis: meeting with the team, studying the current architecture (3–4 hours).
2. Design: dependency diagram, determine lifetimes (2–3 hours).
3. Implementation: write injection_container and tests (1–2 days).
4. Code review and deployment (1 day).
5. Knowledge transfer: documentation and a call (1 hour).

Timelines and Cost

Estimated timeline: 2 to 5 days depending on project size. Cost is calculated individually after a code audit. Debugging time for improper DI can account for up to 30% of team time — our setup pays for itself in the first month by reducing that time. Get a consultation — contact us and we'll offer the optimal solution. Order a turnkey GetIt setup — guaranteed results.

How to choose cross-platform development: Flutter, React Native, or KMM?

We often work with startups that need two apps—iOS and Android—with a budget for one team. Or corporations that want to release an internal tool in three months on both platforms. Cross-platform development solves a specific economic problem: one codebase instead of two. The question is not 'cross-platform or native'—it's 'which tool for which task.'

Each framework dictates its own stack and imposes limitations. An incorrect choice leads to rewriting the project in six months—we've seen it many times with clients who came to us after a failed first attempt. Therefore, before starting, we conduct an audit of technical requirements and team expertise. With 8+ years of cross-platform experience and 50+ delivered apps, we know the pitfalls firsthand.

The three main players now: Flutter, React Native, and Kotlin Multiplatform Mobile. They solve different problems and are poorly compared head-on. Below, we'll break down how to choose the best option for your project.

How do we choose the technology? 4 steps

1. Requirements analysis — list of native APIs, need for offline work, branded UI or standard.
2. Team assessment — expertise in Dart, JavaScript/Kotlin, availability of an iOS developer.
3. Proof-of-concept — implement a critical scenario on the chosen stack in 2–3 days.
4. Final decision — based on performance benchmarks and maintenance cost.

Case from our practice: a fintech startup needed an MVP on both platforms in 10 weeks. Their team had deep React experience, so we selected React Native. The app passed App Store and Google Play review on the first submission, and they launched on schedule. That choice saved 4 weeks compared to training for Flutter.

Comparison of Flutter and React Native: under the hood

Rendering model

Flutter renders UI independently via the Impeller engine (replaced Skia starting with version 3.10). The platform only provides a canvas—Flutter draws every pixel itself. This means:

• Pixel-perfect on all platforms. The same widget looks identical on iOS and Android—good for branded apps, bad if you need a 'native' look on each platform.
• No dependency on OS version. Material 3 in Flutter works the same on Android 8 and Android 14. System Android components are not involved.
• Platform channels for native code. Access to camera, Bluetooth, NFC—via MethodChannel or EventChannel. flutter_camera, flutter_blue_plus are wrappers over platform channels.

React Native uses native platform components. <View> on iOS is UIView. <Text> is UILabel. This means:

• Native look and feel without extra effort.
• New Architecture (Fabric + TurboModules) with JSI removed the JSON bridge between JS and native code. Synchronous calls work without serialization. This is critical for animations and gestures.
• React Native Reanimated 3 runs worklets on the UI thread—animations at 60/120 fps without blocking the JS thread.

Performance in practice

For most business apps, the performance difference between Flutter and React Native New Architecture is imperceptible. The difference appears in edge cases.

Flutter is slower when interacting with platform APIs via platform channels—each call is asynchronous, with data serialization overhead. google_maps_flutter renders the map via PlatformView—a native UIView/View embedded in the Flutter tree. Before Impeller, this caused performance issues (Hybrid Composition vs Virtual Display). With Impeller, Flutter renders UI 2–3x faster on low-end devices compared to Skia, and PlatformView performance improved by 40%.

React Native is slower in scenarios with heavy JS logic on the main thread. Parsing large JSON, complex computations—these block the JS thread and appear as UI freezes. Solution: Hermes (JS engine optimized for RN) + offloading computations to a native module or react-native-workers. With Hermes, cold start time is reduced by 30–40% compared to JavaScriptCore—that's 2x improvement on older devices.

Ecosystem and maturity

Dart is a barrier to entry for teams with a JS/TS background. It's possible to learn basic Dart in a week, but shifting your mindset to Flutter widgets and widget tree takes longer.

TypeScript in React Native is the de facto standard. A team with React experience becomes productive faster.

When to choose Flutter?

• Need a unified branded UI on all platforms (iOS, Android, Web, Desktop).
• Team is ready for Dart.
• Lots of custom animation and custom UI—Flutter is more predictable.
• The app is not tied to specific native APIs.

When to choose React Native?

• Team has React/TypeScript expertise.
• Need native look and feel.
• Heavy use of native components (Maps, Camera with native capabilities).
• Sharing code with React web via monorepo.

Kotlin Multiplatform Mobile: a different story

KMM solves not a UI problem, but the problem of business logic duplication. The concept: write business logic, networking, caching, validation once in Kotlin. iOS receives a .framework via Kotlin/Native, Android uses the library directly. UI on each platform is native.

// Shared Kotlin code — works on iOS and Android
class UserRepository(
    private val httpClient: HttpClient, // Ktor
    private val database: AppDatabase   // SQLDelight
) {
    suspend fun getUser(id: String): User {
        return database.userQueries.selectById(id).executeAsOneOrNull()
            ?: httpClient.get("$BASE_URL/users/$id").body<User>().also {
                database.userQueries.insert(it)
            }
    }
}

Ktor — HTTP client for KMM (works on iOS via Darwin engine, on Android via OkHttp). SQLDelight generates a typesafe Kotlin API for SQLite, works on both platforms.

Real limitations of KMM

Coroutines on iOS: suspend functions from shared code are called through automatically generated wrappers. SKIE (Swift/Kotlin Interface Enhancer) from Touchlab significantly improves the Swift interface: async/await instead of callbacks, AsyncStream for Flow. Without SKIE, working with coroutines from Swift is inconvenient.

Compose Multiplatform: JetBrains is developing Compose for iOS — UI in Compose works on iOS via Metal. This blurs the line with Flutter: one Compose code for both platforms. Status today: Beta, with early adopters in production (Touchlab, JetBrains own products), but stability is lower than Flutter.

Complexity of iOS integration: XCFramework from KMM module is added to an Xcode project. SPM integration exists and works. But iOS developers must understand the Kotlin API and memory management rules via Kotlin/Native (ARC + Kotlin GC work together, which is not always obvious).

When KMM is justified

The company already has mature iOS and Android teams that duplicate business logic. Switching everything to Flutter or React Native is too radical. KMM allows starting small: extract networking and models into shared code, keep UI native. Gradual migration without rewriting everything.

Typical mistakes in technology selection

Choosing Flutter "because it's a single codebase" for an app heavily reliant on native APIs (custom camera, BLE, background processing). Implementing these via platform channels adds complexity that eats up the development speed advantage.

React Native without understanding the JS thread. Heavy operations on the JS thread cause visible freezes. This is solvable, but requires understanding the architecture—otherwise the app will perform worse than native.

KMM without an iOS developer on the team. Shared Kotlin code requires an iOS engineer who integrates the framework into Xcode, writes SwiftUI on top of KMM APIs, and debugs Kotlin/Native crashes.

What is the development process and timeline?

A cross-platform project goes through the same stages as a native one: requirements audit → stack selection → design → development → testing on real devices of both platforms → publication in App Store and Google Play → support.

Testing on real devices is not optional. An emulator does not reproduce memory issues on budget Android phones and does not show differences in gesture behavior on iOS. We test 40+ scenarios on at least 5 real devices covering both OS versions.

Budget savings compared to two native teams can be up to 40–50%. The cost is calculated individually after analyzing the stack and requirements.

What's included in our work

• Technical audit and stack selection for your project.
• Architecture design (clean architecture, MVVM, BLoC/Redux).
• UI development according to design mockups for both platforms.
• Integration of native modules (camera, geolocation, push notifications).
• CI/CD setup (GitHub Actions, Codemagic).
• Testing on real devices (iOS/Android) — at least 40 scenarios.
• Preparation and publication in App Store and Google Play following guidelines (App Store Review, Google Play Policy).
• Technical support for 3 months after launch.
• Handover of source code, documentation, and access — all turnkey.

We'll evaluate your project in one day—get a consultation on stack selection. Order turnkey development and receive a cross-platform app within the agreed timeline, backed by our experience and guaranteed milestones.