import React from 'react';
import { StyleSheet, Text, View } from 'react-native';
import { Notifications } from 'expo';
import * as Permissions from 'expo-permissions';
import Constants from 'expo-constants';

export default class App extends React.Component {

  registerForPushNotificationsAsync = async () => {

    // 実機端末か否かを判定
    if (Constants.isDevice) {

      const { status: existingStatus } = await Permissions.getAsync(Permissions.NOTIFICATIONS);
      let finalStatus = existingStatus;

      // ユーザーによる通知の許可or許可しないが決定していないときのみ
      if (existingStatus !== 'granted') {
        const { status } = await Permissions.askAsync(Permissions.NOTIFICATIONS);
        finalStatus = status;
      }

      // ユーザーが通知許可しなかった場合は処理を抜ける
      if (finalStatus !== 'granted') return;

      // デバイストークンを取得する
      let token = await Notifications.getExpoPushTokenAsync();

      alert(token);

    } else {
      alert('プッシュ通知は、実機端末を使用してください。');
    }
  };

  componentDidMount() {
    this.registerForPushNotificationsAsync();
  }

  render () {
    return (
      <View>
        <Text>Open up App.js to start working on your app!</Text>
      </View>
    );
  }
}

npm i expo-server-sdk

import Expo from 'expo-server-sdk';
//const { Expo } = require('expo-server-sdk')

// Create a new Expo SDK client
let expo = new Expo();

//以下は関数内に設定
// Create the messages that you want to send to clents
let messages = [];
for (let pushToken of somePushTokens) {
  // Each push token looks like ExponentPushToken[xxxxxxxxxxxxxxxxxxxxxx]

  // Check that all your push tokens appear to be valid Expo push tokens
  if (!Expo.isExpoPushToken(pushToken)) {
    console.error(`Push token ${pushToken} is not a valid Expo push token`);
    continue;
  }

  // Construct a message (see https://docs.expo.io/versions/latest/guides/push-notifications.html)
  messages.push({
    to: pushToken,
    sound: 'default',
    body: 'This is a test notification',
    data: { withSome: 'data' },
  })
}

// The Expo push notification service accepts batches of notifications so
// that you don't need to send 1000 requests to send 1000 notifications. We
// recommend you batch your notifications to reduce the number of requests
// and to compress them (notifications with similar content will get
// compressed).
let chunks = expo.chunkPushNotifications(messages);
let tickets = [];
(async () => {
  // Send the chunks to the Expo push notification service. There are
  // different strategies you could use. A simple one is to send one chunk at a
  // time, which nicely spreads the load out over time:
  for (let chunk of chunks) {
    try {
      let ticketChunk = await expo.sendPushNotificationsAsync(chunk);
      console.log(ticketChunk);
      tickets.push(...ticketChunk);
      // NOTE: If a ticket contains an error code in ticket.details.error, you
      // must handle it appropriately. The error codes are listed in the Expo
      // documentation:
      // https://docs.expo.io/versions/latest/guides/push-notifications#response-format
    } catch (error) {
      console.error(error);
    }
  }
})();

...

// Later, after the Expo push notification service has delivered the
// notifications to Apple or Google (usually quickly, but allow the the service
// up to 30 minutes when under load), a "receipt" for each notification is
// created. The receipts will be available for at least a day; stale receipts
// are deleted.
//
// The ID of each receipt is sent back in the response "ticket" for each
// notification. In summary, sending a notification produces a ticket, which
// contains a receipt ID you later use to get the receipt.
//
// The receipts may contain error codes to which you must respond. In
// particular, Apple or Google may block apps that continue to send
// notifications to devices that have blocked notifications or have uninstalled
// your app. Expo does not control this policy and sends back the feedback from
// Apple and Google so you can handle it appropriately.
let receiptIds = [];
for (let ticket of tickets) {
  // NOTE: Not all tickets have IDs; for example, tickets for notifications
  // that could not be enqueued will have error information and no receipt ID.
  if (ticket.id) {
    receiptIds.push(ticket.id);
  }
}

let receiptIdChunks = expo.chunkPushNotificationReceiptIds(receiptIds);
(async () => {
  // Like sending notifications, there are different strategies you could use
  // to retrieve batches of receipts from the Expo service.
  for (let chunk of receiptIdChunks) {
    try {
      let receipts = await expo.getPushNotificationReceiptsAsync(chunk);
      console.log(receipts);

      // The receipts specify whether Apple or Google successfully received the
      // notification and information about an error, if one occurred.
      for (let receipt of receipts) {
        if (receipt.status === 'ok') {
          continue;
        } else if (receipt.status === 'error') {
          console.error(`There was an error sending a notification: ${receipt.message}`);
          if (receipt.details && receipt.details.error) {
            // The error codes are listed in the Expo documentation:
            // https://docs.expo.io/versions/latest/guides/push-notifications#response-format
            // You must handle the errors appropriately.
            console.error(`The error code is ${receipt.details.error}`);
          }
        }
      }
    } catch (error) {
      console.error(error);
    }
  }
})();