React native offline screen wrapper example

connectivityAwareActivityWrapper.js

export default function connectionAwareActivity(WrappedComponent) {
	return class extends PureComponent {
		constructor(props) {
			super(props);
			this.state = { isConnected: false };
			this.switchConnectivity = this.switchConnectivity.bind(this);
		}
		static navigationOptions = WrappedComponent.navigationOptions
		componentDidMount() {
			NetInfo.addEventListener('connectionChange', this.switchConnectivity);
			NetInfo.isConnected.fetch().then(isConnected => {
				this.setState({ isConnected });
			});
		}
		componentWillUnmount(){
			NetInfo.removeEventListener('connectionChange', this.switchConnectivity);
		}
		switchConnectivity(type) {
			if(type === 'none'){
				this.setState({isConnected: false})
			}
			else{
				this.setState({isConnected: true})
			}
		}
		render() {
			return this.state.isConnected ? (
				<WrappedComponent {...this.props} />
			) : (
				<OfflineScreen/>
			);
		}
	};
}

The goal is to wrap around offline screen component into any wrapped component passed. The header should stay as they are in WrappedComponent while the content should show offline design.
I am then using this like-

import{ connectionAwareActivity as cAA } from './sdk'
export default (Router = StackNavigator({
    Splash: {
        screen: cAA(SplashScreen)
    },
    Screen1: {
        screen: cAA(Screen1)
    },
    Screen2: {
        screen: cAA(Screen2)
    },
    ...
})

Problem with this approach is that render is being called twice in offline case, is there any way to know this before the first call to render so that state can be decided initially?
I can use async/await in render, but won't it block UI rendering?

Have you tried replacing componentDidMount with componentWillMount ?
According to lifecycle docs, the componentDidMount runs after the first render, and hence after the first render in componentDidMount you are changing the state, which will result in second render call.
musefind
gitbooks
react component

You should also handle "unknown" case with "none" and by the way fetch() is deprecated:
React native docs

@tejashwikalptaru yes it is, should use getConnectionInfo instead, but both API's return promise or take callback, this is just example code to represent the problem.
I've already tried componentWillMount but placing console.log('render was called') in render function still logs twice on screen navigation.