Getting started

React Native is a popular framework for building mobile applications using JavaScript and React. Whether you're developing for iOS, Android, or both, React Native offers a unified approach that lets you write code once and deploy it across platforms. However, getting started requires choosing the right tools and understanding the ecosystem.

Expo vs React Native CLI

When starting with React Native, you have two main options: Expo and React Native CLI. Both have their own strengths and limitations, so it's essential to choose the one that aligns best with your project's needs.

• Expo is perfect for those looking to develop apps quickly. It simplifies the development process by handling many of the native complexities behind the scenes, allowing you to concentrate on building your app without worrying about the setup of development environments. Still, Expo will be able to handle most functionality that a not-to-advanced-app needs.

• React Native CLI, on the other hand, offers greater control and flexibility. It's the preferred choice if your project requires the integration of native modules or has specific requirements that Expo doesn't support.

Your choice between the two should be guided by factors such as your level of experience, the demands of your project, and the necessity for native features.

Expo explained

Expo is an open-source platform built around React Native. It simplifies the development process by offering a set of tools and services that streamline app development. With Expo, you don't need to install and configure native development environments like Xcode for iOS or Android Studio for Android. This can be a significant time-saver, especially if you're new to mobile development.

Key Features:

• Managed Workflow: Expo handles many of the underlying configurations for you, making it easier to get started.

• Expo Go: A companion app that lets you preview your app on your device without the need for a full build.

• Pre-built Components: Expo includes a range of pre-built components and APIs, such as camera, geolocation, and accelerometer, that work out of the box.

• OTA Updates: Over-the-Air (OTA) updates allow you to push updates to your app without going through the app store review process.

Limitations:

• Limited Native Module Support: If your app requires native modules that are not supported by Expo, you may need to eject from Expo's managed workflow, which can add complexity.

• Size and Performance: Apps built with Expo may have a larger footprint and may not be as optimized as those built directly with React Native CLI.

React Native CLI explained

React Native CLI is the more traditional approach to developing React Native apps. It provides greater flexibility and control, allowing you to dive into native code when necessary. This approach is preferred for production apps, especially when you need to integrate custom native modules or have performance-critical requirements.

Key Features:

• Full Control: With React Native CLI, you have complete access to the iOS and Android project files. This means you can add custom native code, third-party libraries, and more.

• Scalability: Better suited for larger, more complex projects that may need advanced configurations.

• Native Module Integration: Easily add and configure native modules that aren’t supported by Expo.

Challenges:

• Steeper Learning Curve: Requires familiarity with native development environments and tools like Xcode and Android Studio.

• Manual Configuration: You’ll need to handle setup, configuration, and dependency management manually, which can be time-consuming.

Starter kits

Starter kits are pre-configured templates that can accelerate the development process by providing a set of built-in features and best practices. They are particularly useful for beginners or teams that want to kickstart a project quickly.

Popular Starter Kits:

• Ignite CLI: A popular starter kit that provides a comprehensive framework with a set of best practices, pre-configured libraries, and tools. It’s highly customizable and supports both Expo and React Native CLI.

• React Native Boilerplate by TheCodingMachine: A well-structured boilerplate that includes Redux, React Navigation, and more, making it easy to start building scalable applications.

• NativeBase Starter Kit: Focuses on UI development with a library of customizable components that work across both iOS and Android.

These kits often come with sample apps, navigation, state management, and other essential features pre-configured, reducing the initial setup time.

Quirks

React Native is a powerful framework, but it comes with its quirks and challenges. Understanding these can save you time and frustration during development.

• Platform-Specific Behavior: Despite React Native's promise of cross-platform compatibility, certain behaviors and styling can differ between iOS and Android. Testing on both platforms is essential.

• Navigation: React Native's navigation systems, like React Navigation, can sometimes be tricky to configure, especially when dealing with complex, nested navigators.

• Performance: While React Native offers near-native performance, it’s essential to optimize your app by minimizing re-renders, using appropriate image sizes, and being mindful of memory usage.

• Dependency Management: Managing dependencies in React Native can be challenging, especially when dealing with native modules. Conflicts between different versions of dependencies can cause build issues.

• Debugging: Debugging can be more complex than with traditional web development. Tools like Flipper and React Native Debugger can help, but issues like “red screen of death” errors can still be challenging to resolve.

Testing

Testing in React Native is crucial to ensure your app functions correctly across different devices and platforms. Various tools and libraries are available to help with testing.

Types of Testing:

• Unit Testing: Focuses on testing individual components or functions. Tools like Jest and Enzyme (or React Native Testing Library) are commonly used for this purpose.

• Integration Testing: Ensures that different parts of your app work together as expected. React Native Testing Library is useful for writing integration tests.

• End-to-End (E2E) Testing: Simulates real user interactions with your app to ensure that the entire application works as expected. Popular tools include Detox and Appium.

Best Practices:

• Use Mocks: Mocking libraries and API calls can make your tests more reliable and faster.

• Test on Multiple Devices: Since your app will run on different screen sizes and platforms, testing on a variety of devices and simulators is crucial.

• Continuous Integration (CI): Integrate your tests into a CI pipeline to automate testing with every code change. Tools like CircleCI, GitHub Actions, or Jenkins can be used to set this up.