App.js

import React from 'react';
import { StyleSheet, View } from 'react-native';
import { Container, Header, Left, Body, Right, Button, Icon, Title } from 'native-base';

export default class App extends React.Component {
  async componentWillMount() {
    await Expo.Font.loadAsync({
      'Roboto': require('native-base/Fonts/Roboto.ttf'),
      'Roboto_medium': require('native-base/Fonts/Roboto_medium.ttf'),
    });
  }
  render() {
    return (
      <Container>
        <Header>
          <Left>
            <Button transparent>
              <Icon name='arrow-back' />
            </Button>
          </Left>
          <Body>
            <Title>
              <Icon name='logo-apple' />
            </Title>
          </Body>
          <Right>
            <Button transparent>
              <Icon name='menu' />
            </Button>
          </Right>
        </Header>
      </Container>
    );
  }
}

const styles = StyleSheet.create({
  container: {
    flex: 1,
    backgroundColor: '#fff',
    alignItems: 'center',
    justifyContent: 'center',
  },
});