js__react_native__fb/basics/App07Flex.js

import React from 'react';
import { View } from 'react-native';

class FlexDimensionsBasics extends React.Component {
  render() {
    return (
      // Try with height: 300 instead of flex: 1
      <View style={{ flex: 1 }}>
        <View style={{ flex: 1, backgroundColor: 'powderblue' }} />
        <View style={{ flex: 2, backgroundColor: 'skyblue' }} />
        <View style={{ flex: 3, backgroundColor: 'steelblue' }} />
      </View>
    );
  }
}

export default FlexDimensionsBasics;