Optimizations in React Native - Part 2

Optimizing images in React Native applications is crucial for improving performance and user experience. Here are some tips and techniques for effectively adjusting the size of images: 1. **Use of Optimized Image Formats**: Opt for modern and efficient image formats like WebP (yes, WebP is supported in React Native 😎, but it requires some configuration adjustments, we'll talk about it in another article) or JPEG 2000. These formats offer a good balance between quality and file size. 2. **Resizing Images**: Reduce the physical size of images. It's unnecessary to load a 4000x3000 pixel image for a display that only requires 800x600. Use server-side image resizing tools or incorporate a resizing step in your deployment pipeline. 3. **Lossless Compression**: Use lossless compression to reduce file sizes without sacrificing quality. Tools like TinyPNG or ImageOptim can be helpful. 4. **Lazy Loading**: Implement lazy loading of images. This means images are only loaded when they enter the user's viewport. In React Native, you can use libraries like **`react-native-lazy-load-image`**. > 💡 Small tip: Again, it is important to properly balance the use of external libraries. It's important not to reinvent the wheel, but the use of external dependencies can sometimes be detrimental to the project. > 5. **Image Caching**: Cache images after their first download. This avoids reloading the same images each time, thus saving network resources and speeding up loading time. 6. **Use of Thumbnails**: For lists of images, like in a gallery, use small-size thumbnails that can be expanded at the user's request. 7. **Performance Monitoring**: Use tools like Flipper or React Native Performance to monitor the impact of your images on the application's performance. By implementing these practices, you can significantly improve the performance of your React Native application, especially regarding loading times and the smoothness of the user interface.

Caching images locally is an important strategy for optimizing the performance of React Native applications. Libraries 📚 like **`react-native-fast-image`** offer advanced caching functionalities. **`FastImage`** replaces the standard image component of React Native and manages the image cache more efficiently. You can also determine the cache strategy suitable for your application. You can choose to cache up to a certain size threshold or for a specific duration before refreshing the cache. Persistent storage on the device for storing images is another solution. Options like AsyncStorage or local databases like Realm or SQLite can be used to store image metadata and their paths. Finally, monitor and manage the size of your cache to avoid excessive use of storage space on the device. Implement logic to purge less frequently used images from the cache.