As the name suggests, React Native is used to build native applications in iOS and Android platforms using JavaScript and ReactJS. Some of the key features of React Native, favored by the Facebook developer teams (https://facebook.github.io/react-native/) for the native platforms, are mentioned here:
It has the power of consistency in look and feel using React component counterparts
You can develop the app using Chrome developer tools and run in a simulator
There is asynchronous execution of all the code between the application and the native platform
React Native seamlessly handles touch events, polyfills, StyleSheet abstraction, designing common UI layouts
It's widely used to extend native code creating iOS and Android modules and views and reusing them later, with ease
React Native's qualities of being declarative, asynchronous, and responsive are highly beneficial for iOS development