App.js

import React from 'react';
import { AppLoading } from 'expo';
import * as Font from 'expo-font';
import { Ionicons } from '@expo/vector-icons';
import { Root } from 'native-base';

import Navigator from './Navigator';
import { StateProvider } from './state';
import reducer, { initialState } from './reducer';

export default class App extends React.Component {
  constructor(props) {
    super(props);
    this.state = {
      isReady: false,
    };
  }

  async componentDidMount() {
    await Font.loadAsync({
      Roboto: require('native-base/Fonts/Roboto.ttf'),
      Roboto_medium: require('native-base/Fonts/Roboto_medium.ttf'),
      ...Ionicons.font,
    });

    this.setState({ isReady: true });
  }

  render() {
    if (!this.state.isReady) {
      return <AppLoading />;
    }

    return (
      <Root>
        <StateProvider reducer={reducer} initialState={initialState}>
          <Navigator />
        </StateProvider>
      </Root>
    );
  }
}