$ npm install react-native-sf-authentication-session --save

$ react-native link react-native-sf-authentication-session

1. In XCode, in the project navigator, right click Libraries ➜ Add Files to [your project's name]
2. Go to node_modules ➜ react-native-sf-authentication-session and add RNSFAuthenticationSession.xcodeproj
3. In XCode, in the project navigator, select your project. Add libRNSFAuthenticationSession.a to your project's Build Phases ➜ Link Binary With Libraries
4. Run your project (Cmd+R)<

import RNSFAuthenticationSession from 'react-native-sf-authentication-session';

...
// The url you want to open with safari
const url = "http://my.webapp.com"
// The url your server will redirect you to
// hint - use a custom schema or universal link to immediatly get back to your app
const callbackUrl = "myapp://"
// The redirected url with query params containing private data
// ex - "myapp://token=mysecrettoken"
const finalUrl = await RNSFAuthenticationSession.getSafariData();