register.js

import { Util, Permissions, Notifications, Constants } from 'expo'

export const registerForPushNotificationsAsync = async () => {
  const { status: existingStatus } = await Permissions.getAsync(
    Permissions.NOTIFICATIONS
  )
  let finalStatus = existingStatus

  if (existingStatus !== 'granted') {
    const { status } = await Permissions.askAsync(Permissions.NOTIFICATIONS)
    finalStatus = status
  }

  if (finalStatus !== 'granted') {
    return
  }

  let token = await Notifications.getExpoPushTokenAsync()

  const zone = await Util.getCurrentTimeZoneAsync()
  const res = await fetch(
    'https://<my-url>.amazonaws.com/dev/subscribe',
    {
      method: 'POST',
      headers: {
        Accept: 'application/json',
        'Content-Type': 'application/json',
      },
      body: JSON.stringify({
        token,
        zone,
        deviceId: Constants.deviceId,
        deviceName: Constants.deviceName,
      }),
    }
  )

  console.log('registered!')
  return await res.json()
}