Have you clone project from github or download zip project and immediately you stated running the project and the next thing you see in Xcode is "Lexical or preprocessor error

React native RTCRootView.h not found "

Solution :

In the example directory run npm install to install the dependencies. Then open YourExampleProject.xcodeproj and run. And now you good to go.

Now, focus on your next ONE thing.

 

Learn React Native

React Native - React Native is a mobile framework from facebook to create native iOS and Android mobile apps(till to date).

React Native is based on Javascript React Framework, created to overcome the hurdles of Mobile development.

React Native is an Declarative Programming rather than traditional Imperative Programming.
Declarative programing focuses on What the program should accomplish. Ex: React
Imperative  programing focuses on How the program operates  Ex: DOM

React Native is NOT Write Once, Run Everywhere paradigm; It's Learn Once, Write Everywhere paradigm.

React Native is an Asynchronous, Batched and Serializable bridge; which acts as a bridge between JS framework and native APIs.

Below are the list of videos that helps you to understand more about ReactNative.
https://www.youtube.com/watch?v=n5RhAYhTxCk
https://www.youtube.com/watch?v=hDviGU-57lU
https://www.youtube.com/watch?v=X6YbAKiLCLU
https://www.youtube.com/watch?v=oWPoW0gIzvs
https://youtu.be/oWPoW0gIzvs