With the React Native SDK already installed, initializing a new React Native project is as simple as using the following command line:
react-native init Tasks
Let the React Native command line interface do its work for a few moments, then open the directory titled Tasks once it is completed.
From there, running your app in iOS Simulator is as easy as typing the following command:
This will start a process to build and compile your React Native app, launch the iOS Simulator, import your app to the Simulator, and start it. Whenever you make a change to the app, you will be able to reload and see those changes immediately.