Custom components in React Native - Build, Publish & Deploy

Build & Publish - Custom components

Performance Impact of Custom Components

Using custom components helps organize your app UI into smaller pieces. This can improve performance by reducing repeated code and making updates easier. However, creating too many small components can add overhead, causing slower rendering and more memory use. Aim for a balance: components should be reusable but not too tiny.

React Native targets 60 frames per second for smooth animations. Complex custom components with heavy logic or many nested views can drop frames and cause jank. Keep components simple and avoid unnecessary re-renders to maintain smooth UI.

How to Optimize Custom Components for 60fps Rendering

• Use React.memo to prevent re-rendering components when props don't change.
• Keep components focused on one task to reduce complexity.
• Avoid inline functions and objects in props to prevent unnecessary updates.
• Use the useCallback and useMemo hooks to memoize functions and values.
• Minimize the number of nested views inside components to reduce layout calculations.
• Profile your app with React DevTools and React Native Performance Monitor to find slow components.

Impact on App Bundle Size and Startup Time

Custom components themselves add very little to app size since they are just JavaScript code. However, importing many third-party components or large UI libraries inside custom components can increase bundle size significantly.

More components can increase startup time if many are loaded immediately. Use lazy loading or code splitting to load components only when needed, improving startup speed.

iOS vs Android Differences for Custom Components

React Native custom components work similarly on both iOS and Android because they use the same JavaScript code. However, native UI differences can affect appearance and behavior.

For example, some native components like Picker or Switch look different on each platform. Custom components wrapping these should handle platform-specific styles or behaviors using Platform.select.

Performance may vary slightly due to native rendering differences, so test your custom components on both platforms.

Relevant Store Review Guidelines and Requirements

• Apple App Store: Ensure your custom components do not use private APIs or undocumented features. Follow Apple's Human Interface Guidelines for UI consistency and accessibility.
• Google Play Store: Avoid components that cause crashes or excessive battery use. Follow Material Design guidelines for UI and accessibility.
• Both stores require apps to be responsive and accessible. Use proper accessibility props in custom components (like accessibilityLabel and accessible).
• Make sure custom components handle different screen sizes and orientations gracefully.

Self-Check: Your App Takes 5 Seconds to Load This Screen. What's Likely Wrong?

It's likely your custom components are doing too much work on mount or rendering too many nested views. Possible issues:

• Heavy computations or data fetching inside component render functions.
• Not using memoization, causing repeated re-renders.
• Loading large images or assets synchronously in components.
• Too many nested components causing slow layout calculations.

To fix, move heavy work outside render, use React.memo, lazy load assets, and simplify component trees.

Key Result

Custom components improve code reuse and app structure but must be optimized with memoization and simple layouts to maintain 60fps performance and small bundle size. Test on both iOS and Android for UI differences and follow store guidelines for accessibility and responsiveness.