2. [Homebrew](http://brew.sh/) is the recommended way to install nvm, watchman, and flow.
3. Install [Node.js](https://nodejs.org/) 4.0 or newer.
- Install **nvm** with Homebrew or [its setup instructions here](https://github.com/creationix/nvm#installation). Then run `nvm install node && nvm alias default node`, which installs the latest version of Node.js and sets up your terminal so you can run it by typing `node`. With nvm you can install multiple versions of Node.js and easily switch between them.
4.`brew install watchman`. We recommend installing [watchman](https://facebook.github.io/watchman/docs/install.html), otherwise you might hit a node file watching bug.
5.`brew install flow`. If you want to use [flow](http://www.flowtype.org).
[Xcode](https://developer.apple.com/xcode/downloads/) 6.3 or higher is required. It can be installed from the App Store.
## Android Setup
To write React Native apps for Android, you will need to install the Android SDK (and an Android emulator if you want to work on your app without having to use a physical device). See [Android setup guide](android-setup.html) for instructions on how to set up your Android environment.
## Adding Android to an existing React Native project
If you already have a (iOS-only) React Native project and want to add Android support, you need to execute the following commands in your existing project directory:
1. Update the `react-native` dependency in your `package.json` file to [the latest version](https://www.npmjs.com/package/react-native)