The development of cross-platform mobile applications has always been a source of many challenges. Although tools like Apache Cordova and Haxe do solve some of the associated issues, they are still not the ideal solution in many cases. React Native changes that by providing the power of React.js for mobile platforms and a promise of consistent developer experience across multiple platforms.
It is not uncommon for developers to find themselves in need of a UI component that is either not provided by the platform they are targeting or is, indeed, provided, but lacks a certain property or behavior. The answer to both scenarios is a custom UI component. The Android UI model is inherently customizable, offering the means to create custom UI components in various ways.