React Native

React Native enables you to build world-class application experiences on native platforms using a consistent developer experience based on JavaScript and React. The focus of React Native is on developer efficiency across all the platforms you care about — learn once, write anywhere. Facebook uses React Native in multiple production apps and will continue investing in React Native.

Requirements 

1. OS X - This repo only contains the iOS (7+) implementation right now, and Xcode only runs on Mac.
2. Xcode 6.3 or higher is recommended.
3. Homebrew is the recommended way to install node, watchman, and flow.
4. brew install iojs && brew link iojs --force. You may need to run brew unlink node if you have previously installed Node. New to io.js or npm?
5. brew install watchman. We recommend installing watchman, otherwise you might hit a node file watching bug.
6. brew install flow. If you want to use flow.

Quick start 

• npm install -g react-native-cli
• react-native init AwesomeProject

In the newly created folder AwesomeProject/

• Open AwesomeProject.xcodeproj and hit run in Xcode.
• Open index.ios.js in your text editor of choice and edit some lines.
• Hit cmd+R in your iOS simulator to reload the app and see your change!

Congratulations! You've just successfully run and modified your first React Native app.

If you run into any issues getting started, see the troubleshooting page.

Ref:http://facebook.github.io/react-native/