Cross-Platform: What is It?

What is Cross-Platform Development?

Cross-platform development is a mobile development approach that involves writing a single codebase capable of running on multiple operating systems, primarily iOS and Android. Rather than developing two separate applications with different languages (Swift for iOS, Kotlin for Android), developers use an intermediary framework that translates or compiles code for each target platform.

This approach has evolved considerably since the early hybrid solutions based on WebViews (Cordova, PhoneGap). Modern frameworks like React Native and Flutter produce genuinely native interfaces and deliver performance close to native development. Cross-platform is now the recommended default strategy for the majority of mobile application projects, except for cases requiring highly specific native integrations.

Why Cross-Platform Matters

Mobile development represents a substantial investment for businesses. Cross-platform is the most pragmatic answer to the cost/coverage/quality equation that every company must solve when considering a mobile application.

• 30 to 50% cost reduction: A single team develops and maintains one codebase instead of two. The saved budget can be reinvested in additional features or marketing.
• Reduced time-to-market: A feature developed once is deployed simultaneously on both platforms, halving delivery time.
• Functional consistency: iOS and Android users benefit from exactly the same features, with no gap between versions. Bugs are fixed once.
• Simplified maintenance: A single codebase to maintain, a single test suite, a single technical documentation. Updates are deployed in parallel to both stores.
• Technical flexibility: Modern frameworks allow integrating native code (Swift, Kotlin) for features that require it, offering the best of both worlds.
• Easier recruitment: JavaScript/TypeScript developers (React Native) are more plentiful on the market than specialised Swift or Kotlin developers, making team building and rotation easier.

How It Works

Modern cross-platform frameworks use distinct technical approaches to produce applications running on both platforms.

React Native adopts a bridge approach: JavaScript code runs in a JS engine and communicates with the platform's native components via an interface (JSI since the new architecture). React components are translated into native UIKit (iOS) or Android View (Android) components. The result is an application that uses the real native components of each platform.

Flutter uses a custom rendering engine (Skia/Impeller) that draws every pixel of the interface. Components are not native components but faithful reproductions drawn by the engine. This approach offers pixel-perfect control but may diverge from the native look and feel expected by users of each platform.

At Kern-IT, we favour React Native for its synergies with our React web expertise. Our frontend developers master React and can contribute to mobile code without a language change. Business logic, TypeScript types, and some components can be shared between the web and mobile applications, creating a coherent and efficient development ecosystem.

Concrete Example

Consider a Belgian startup in the mobility sector launching a ride-sharing service. It needs to offer an application for passengers and an application for drivers, available on iOS and Android. With a native approach, this represents four distinct development projects.

With React Native, the company develops two applications (passenger and driver) sharing 80% of their code: API services, state management, business logic, and many UI components. Only profile-specific screens and native integrations (background geolocation for drivers, Apple Pay/Google Pay for payments) are differentiated. The Django backend, developed in parallel by Kern-IT, exposes a unified REST API. Everything is delivered in 4 months with a team of 5, where native development would have required 8 months and two separate teams.

Implementation

1. Assess native requirements: List critical features and verify they are supported by the chosen cross-platform framework. Cases requiring native code are identified at this stage.
2. Choose the framework: React Native if the team knows React/JavaScript, Flutter if the team is ready to adopt Dart, or PWA if needs are primarily web-based.
3. Structure the architecture: Clearly separate shared business logic from platform-specific components. Use a modular architecture that facilitates adding native modules.
4. Develop necessary native modules: For features not covered by community libraries, develop native modules in Swift and Kotlin.
5. Test on both platforms: Each feature must be validated on iOS and Android. Automated end-to-end tests cover both platforms.
6. Deploy in parallel: Configure CI/CD pipelines to build and publish simultaneously to the App Store and Google Play Store.

Associated Technologies and Tools

• React Native: Meta's cross-platform framework, using JavaScript/TypeScript and native components.
• Flutter: Google's cross-platform framework, using Dart and a custom rendering engine.
• Expo: Development platform that significantly simplifies the React Native workflow.
• TypeScript: Typed superset of JavaScript, essential for cross-platform projects of significant size.
• Fastlane: Build and deployment automation for both mobile stores.
• CodePush / EAS Update: Over-the-air JavaScript code updates without going through the stores, enabling rapid fixes.

Conclusion

Cross-platform development has become the default strategy for the majority of mobile application projects. Modern frameworks like React Native and Flutter have bridged the performance gap with native, while offering considerable cost and time savings. At Kern-IT, we guide our Belgian and European clients in choosing and implementing the cross-platform strategy best suited to their context. Our standard recommendation is React Native, which offers the best compromise between performance, productivity, and synergy with the React web ecosystem. Native remains relevant for specific cases requiring advanced platform integrations, but it should no longer be the default choice.