Xamarin App Support and Migration to .NET MAUI

A legacy Xamarin project either needs support or a transition to a modern stack. Microsoft documentation confirms Xamarin.iOS and Xamarin.Android provide direct bindings to native SDKs — no bridge, no intermediate runtime except Mono. This sets them apart from React Native or Cordova: you work with the same UIViewController, UITableView, RecyclerView, ConstraintLayout as in native development, just in C# instead of Swift/Kotlin. Xamarin.Forms adds a shared UI layer on top, but at the cost of losing direct control over each native widget.

Xamarin no longer receives updates from Microsoft, so support and migration require specialized experience. Our team maintains Xamarin-based applications and performs porting to .NET MAUI with documentation of each step and a 30-day warranty. Experience — over 30 projects on Xamarin over 5 years, saving clients up to 40% compared to maintaining two native teams. Typical migration costs start from $5,000 for small apps, with annual savings of up to $20,000 by consolidating to a single MAUI codebase. Our support packages start at $2,500 per year for small apps with up to 5 dependencies.

Supporting existing Xamarin projects

Maintaining a legacy Xamarin app today is a specific task. Key issues:

Outdated NuGet packages. Some packages are no longer updated for Xamarin.iOS 16+ and Android API 33+. A typical example is Xamarin.Forms.GoogleMaps: the last stable release was issued before active support ended, and on Android 13 runtime crashes occur due to changes in geolocation permissions. We must fork, patch, or replace with alternatives.

iOS breaking changes.** Apple continues to tighten requirements for privacy manifests — any app using NSUserDefaults, FileTimestamp, SystemBootTime and other APIs without PrivacyInfo.xcprivacy gets warnings when uploading to App Store Connect, then rejection. In Xamarin.iOS, PrivacyInfo.xcprivacy is added manually as a BundleResource.

Mono runtime and ARM64. Xamarin.iOS compiles to native ARM64 via AOT — no issues there. Xamarin.Android uses a Mono runtime with JIT on ARM, which means larger app size and slow cold start — .NET MAUI on .NET 8 AOT is 1.5x faster in cold start speed.

What's included in Xamarin app support?

When ordering support, we provide:

• Updating target SDKs (TargetFramework, minSdkVersion/targetSdkVersion)
• Patching dependencies and forking outdated packages
• Adding PrivacyInfo.xcprivacy for iOS
• Fixing deprecated APIs (e.g., UIWebView → WKWebView)
• Auditing permissions for Android 13/14 with the new model (READ_MEDIA_IMAGES, POST_NOTIFICATIONS)
• Configuring CI for Xamarin: msbuild / xcodebuild via Azure DevOps or GitHub Actions with Fastlane
• Documenting all changes and providing a report

We train your team to work with the updated code. After the first year of support, maintenance costs decrease by an average of 25%. Contact us for a free audit of your project.

Why migrate from Xamarin to .NET MAUI?

Migration is not just running dotnet-upgrade-assistant. Yes, Microsoft provided a tool with the command upgrade-assistant upgrade --non-interactive — it rewrites csproj, updates namespaces from Xamarin.* to Microsoft.Maui.*, but requires manual fixes in 30–50% of cases. The decision to migrate depends on the app's future: if you plan active development, .NET MAUI is the better choice.

The migration process consists of five stages:

1. Code audit – assess the workload, identify custom renderers, DependencyService, Xamarin.Essentials.
2. Run upgrade-assistant – automatic update of project files and initial refactoring.
3. Manual refinement – replace Renderer with Handler, translate platform-specific code, update build configurations.
4. Testing – test on real devices (iOS 16+, Android 13+), including scenarios for push, deep linking, in-app purchase.
5. Deployment – publish to TestFlight and Google Play Console, set up monitoring.

The most work-intensive parts of porting:

• Replacing Renderer with Handler
• Translating Xamarin.Essentials to MAUI Essentials (APIs are compatible, but namespaces changed)
• Working with platform-specific code in DependencyService — in MAUI this is replaced by partial class or native MauiProgram.cs hooks.

Comparison Xamarin vs .NET MAUI

Xamarin.Forms is significantly outperformed by .NET MAUI — cold start is 30–40% slower on Android, which is critical for users.

What are the main migration stages?

Transition timelines range from 4 weeks (small app without custom renderers) to 3–4 months (large product with deep native integration). Cost is calculated individually after auditing the existing code and assessing the volume of changes.

Typical mistakes when migrating Xamarin to MAUI

• Forgetting to update all DependencyService to partial class — app crashes on first access to platform service.
• Not adding PrivacyInfo.xcprivacy — rejection in App Store.
• Leaving outdated packages like Xamarin.Essentials — they need to be replaced with Microsoft.Maui.Essentials.
• Not updating ProGuard/R8 build configuration (Android) — may cause shrink-removal errors.

Get a consultation on your Xamarin project. We will assess the scope, risks, and timelines. Contact us — we will conduct a free code audit and offer options: support or turnkey migration.

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.