How to use the onsenui.platform.isIOS function in onsenui

import {platform} from 'onsenui';

import {
  Page,
  ProgressCircular
} from 'react-onsenui';

import NavBar from '../components/NavBar';
import WeatherIcon from '../components/WeatherIcon';
import Forecast from '../components/Forecast';
import {weatherCodeToColor} from '../util';

const styles = {
  main: {
    fontFamily: platform.isIOS() ? 'Lato' : null,
    textAlign: 'center',
    color: '#4a4a4a',
    width: '100%',
    marginTop: '30px'
  },
  invalid: {
    color: 'red',
    fontSize: '20px'
  },
  progress: {
    width: '50px',
    height: '50px'
  },
  name: {
    textTransform: 'uppercase',
    fontSize: '24px',