Moving from React Native to Swift & Kotlin: What You Need to Know

Some of the most popular apps in the world started with React Native, but not all of them stayed there. The shift to Swift and Kotlin isn’t just a technical decision—it’s often about pushing an app’s performance, stability, and scalability to the next level. If your team is thinking about moving away from React Native, knowing what’s ahead can help you avoid pitfalls and make the transition smoother.

Why Move from React Native to Swift & Kotlin?

React Native is a great choice for cross-platform development. It speeds up development time, allows for a single codebase across iOS and Android, and comes with a strong ecosystem. But as an app grows, teams often run into limitations.

• Performance Bottlenecks: React Native relies on a JavaScript bridge to communicate with native modules, which can cause lag, especially in animations and complex UI interactions.
• Platform-Specific Features: Some advanced iOS and Android capabilities require deep integration with native APIs, making JavaScript-based workarounds inefficient.
• App Stability & Maintenance: Frequent React Native updates and breaking changes can introduce unexpected issues, requiring constant maintenance.
• Scaling Challenges: As an app expands, managing dependencies and ensuring a consistent experience across both platforms can become time-consuming.

Preparing for the Transition

Switching from React Native to Swift and Kotlin isn’t just about rewriting code—it’s about rethinking how the app is structured. Before diving in, it’s best to have a clear plan.

Evaluate Your Existing Codebase

Not everything needs to be rewritten at once. A hybrid approach can work, allowing teams to migrate features gradually instead of rebuilding the entire app from scratch.

• Identify which features benefit most from native implementation.
• Look for dependencies on third-party libraries that may need native replacements.
• Assess performance bottlenecks in the current app that native code can improve.

Understand the Learning Curve

Swift and Kotlin have different syntax and patterns than JavaScript, so developers moving from React Native may need time to adjust.

• Swift follows a strongly typed, safe-by-default approach, reducing runtime crashes.
• Kotlin is expressive and interoperable with Java, making it a powerful choice for Android development.
• State management changes—React Native often uses Redux or Context API, but Swift and Kotlin rely on other patterns like Combine, SwiftUI state, or ViewModel and LiveData.

Breaking Down the Migration Process

Moving from JavaScript to Swift

React Native developers familiar with JavaScript may find Swift’s strict typing and optionals a bit of an adjustment. However, Swift’s readability and safety mechanisms reduce runtime errors.

Key Differences in Language Structure

• Types & Optionals: Swift enforces type safety, while JavaScript allows dynamic typing.
• Memory Management: JavaScript uses garbage collection, while Swift uses Automatic Reference Counting (ARC).
• Concurrency: JavaScript relies on an event loop, whereas Swift’s Grand Central Dispatch (GCD) and async/await handle multithreading more efficiently.

Transitioning UI Components

React Native components like <View>, <Text>, and <Button> translate to SwiftUI or UIKit components in Swift.

• <View> → UIView (UIKit) or VStack/HStack/ZStack (SwiftUI)
• <Text> → UILabel (UIKit) or Text (SwiftUI)
• <Button> → UIButton (UIKit) or Button (SwiftUI)

For teams looking for a more declarative UI similar to React Native, SwiftUI is the closest alternative. UIKit remains the standard for more mature and complex apps.

Migrating from JavaScript to Kotlin

On the Android side, React Native components and logic need to be restructured using Kotlin’s idiomatic features.

Key Differences in Language Structure

• Null Safety: Kotlin enforces null safety, reducing runtime crashes.
• Coroutine Support: JavaScript uses Promises and async/await, while Kotlin uses coroutines for managing asynchronous tasks.
• Type Inference: Kotlin allows type inference similar to JavaScript’s let and const, but with strict typing.

Rebuilding Android UI

React Native’s UI components like <View> and <Text> map to Android’s XML-based layouts or Jetpack Compose.

• <View> → LinearLayout, ConstraintLayout, or Box (Jetpack Compose)
• <Text> → TextView (XML) or Text (Jetpack Compose)
• <Button> → Button (XML) or Button (Jetpack Compose)

Jetpack Compose brings a more React-like approach to UI development on Android, making it a smoother transition for React Native developers.

Handling Data & State Management

State management in React Native typically revolves around Redux, Context API, or libraries like Recoil or Zustand. In Swift and Kotlin, the approach shifts.

Swift State Management

• SwiftUI State: Uses @State, @Binding, @ObservedObject, and @EnvironmentObject.
• Combine Framework: Handles reactive programming and state changes efficiently.
• Core Data / Realm: Manages local persistence without external libraries.

Kotlin State Management

• ViewModel & LiveData: Separates UI logic from data handling.
• StateFlow & SharedFlow: Kotlin’s alternative to RxJava for handling reactive state.
• Room Database: Provides an efficient ORM for local persistence.

Handling API Calls & Networking

React Native developers often use Axios or the built-in fetch API. In Swift and Kotlin, different tools handle networking.

Swift API Calls

• URLSession: The standard way to make network requests.
• Alamofire: A popular networking library for Swift.
• Combine & Async/Await: Allows cleaner and more readable asynchronous code.

Kotlin API Calls

• Retrofit: The go-to library for making API calls in Kotlin.
• Ktor: A modern alternative for handling HTTP requests.
• Coroutines & Flow: Makes network calls more efficient by avoiding callback hell.

Managing Dependencies & Third-Party Libraries

One of the challenges when moving to Swift and Kotlin is replacing React Native’s JavaScript-based libraries with native alternatives.

• React Navigation → UINavigationController (iOS) / NavController (Android)
• AsyncStorage → UserDefaults (iOS) / SharedPreferences (Android)
• Axios / Fetch → URLSession (Swift) / Retrofit (Kotlin)
• React Native Gesture Handler → UIPanGestureRecognizer (Swift) / MotionEvent (Kotlin)

Testing & Debugging the New Codebase

React Native developers are used to hot reloading and browser-based debugging tools. Swift and Kotlin have different debugging methods.

Debugging in Swift

• Xcode Instruments: Profiles performance and detects memory leaks.
• LLDB Debugger: Provides a powerful debugging tool inside Xcode.
• View Debugger: Helps analyze UI hierarchy and layout issues.

Debugging in Kotlin

• Android Studio Profiler: Tracks memory usage, CPU, and network activity.
• Logcat: Provides detailed logs for app behavior.
• Breakpoint Debugging: Allows step-through debugging inside Android Studio.

Deployment & CI/CD Adjustments

Switching from React Native to Swift & Kotlin also means adjusting the CI/CD pipeline.

iOS Deployment

• Build and sign apps using Xcode & Fastlane.
• Manage dependencies using CocoaPods or Swift Package Manager.
• Automate testing with XCTest & Firebase Test Lab.

Android Deployment

• Build and sign APKs with Gradle & Fastlane.
• Manage dependencies using Gradle.
• Automate testing with Espresso & Firebase Test Lab.

Final Thoughts

Moving from React Native to Swift and Kotlin isn’t just about rewriting an app—it’s about making it stronger, faster, and more adaptable to platform-specific features. The process takes time, but breaking it down into manageable steps makes it easier. Whether it’s improving performance, refining UI interactions, or leveraging native APIs, the shift to Swift and Kotlin can open new possibilities for an app’s growth.