Once you have your React Native project initialized, you can run `react-native run-ios` inside the newly created project directory. If everything is set up correctly, you should see your new app running in the iOS Simulator shortly.
You can specify the device the simulator should run with the `--simulator` flag, followed by the device name as a string. The default is `"iPhone 6"`. If you wish to run your app on an iPhone 4s, just run `react-native run-ios --simulator="iPhone 4s"`.
The device names correspond to the list of devices available in Xcode. You can check your available devices by running `xcrun simctl list devices` from the console.
