Note that running on device requires [Apple Developer account](https://developer.apple.com/register) and provisioning your iPhone. This guide covers only React Native specific topic.
When you run your app on device, we pack all the JavaScript code and the images used into the app's resources. This way you can test it without development server running and submit the app to the AppStore.
3. The JS bundle will be built for dev or prod depending on your app's scheme (Debug = development build with warnings, Release = minified prod build with perf optimizations). To change the scheme navigate to `Product > Scheme > Edit Scheme...` in xcode and change `Build Configuration` between `Debug` and `Release`.
When building your app for production, your app's scheme should be set to `Release` as detailed in [the debugging documentation](/react-native/docs/debugging.html#debugging-react-native-apps) in order to disable the in-app developer menu.
Note that since [v0.14](https://github.com/facebook/react-native/releases/tag/0.14.0) JS and images are automatically packaged into the iOS app using `Bundle React Native code and images` Xcode build phase.