QRcodescanner.js

import React from 'react';
import QRCodeScanner from 'react-native-qrcode-scanner';
import RNCamera  from 'react-native-camera';
import {
  TouchableOpacity,
  View,
  Text,
} from 'react-native';
import WebView from 'react-native-webview'


export default class App extends Component {
  state = {
    webview: false,
    url: ''
  }
  onSuccess = e => {
    this.setState({url: e.data, webview: true})
  };

    
  render() {
    return (
      <View style={{flex:1}}>
        <View style={{flex:1}}>
        {this.state.webview && (<WebView 
            source={{uri: this.state.url}}
            style={{flex:1}}
            scalesPageToFit={true} />
            )}
      

            {!this.state.webview && (<QRCodeScanner
        onRead={this.onSuccess.bind(this)}
        reactivate={true}
        reactivateTimeout={4000}/>
         
          )}
        <TouchableOpacity
            style={{
              alignItems: 'center',
              justifyContent: 'center',
              backgroundColor: 'rgba(0,0,0,0.2)',
              borderRadius: 50,
              width: 75,
              height: 75,
              position: 'absolute',
              right: 5,
              bottom: 5
            }}
            onPress={() => this.setState({ webview: false })}
            >
              <Text style={{textAlign: 'center'}}>Click to Reload</Text>
          </TouchableOpacity>
          
  
    </View>
  
    </View>
    );
  }
}