处理前台与后台通知
使用 addNotificationReceivedListener 处理应用打开时收到的通知，并使用 addNotificationResponseReceivedListener 响应用户点击通知的操作。
处理前台与后台通知 是 CoddyKit 上的免费 React Native Academy 课时。 这是第 3 节课，共 4 节。 你可以在下方免费阅读本课时的完整内容 — 然后在浏览器中使用内置代码编辑器和全天候 AI 导师进行实践。 这是 React Native Academy 学习路径的一部分，你的进度在网页和 CoddyKit 应用中同步。 React Native Academy 课程共包含 4 节课。
本课时的部分内容尚未翻译，以英文显示。
App States and Notification Delivery
Your app can be in three states when a notification arrives: foreground (app is open and visible), background (app is running but not visible), or killed (app is not running at all). Each state has different handling requirements and different APIs to use.
Understanding which state applies is critical because the OS delivers notifications differently in each case and the user's tap response routes through different code paths depending on the app state at the time they tap.
addNotificationReceivedListener
Notifications.addNotificationReceivedListener fires when a notification arrives while the app is in the foreground. By default, notifications do not show a banner or sound when the app is already open — you must handle them in-app. The listener receives the full notification object including all content and data payload.
Use this to show in-app banners, update UI (e.g., refresh a chat thread), or play a custom sound — giving users the same experience as if the notification had arrived while the app was in the background.
import * as Notifications from 'expo-notifications';
import { useEffect } from 'react';
useEffect(() => {
const subscription = Notifications.addNotificationReceivedListener(
(notification) => {
const { title, body, data } = notification.request.content;
console.log('Notification received in foreground:', title, body);
// Update UI or show in-app banner:
showInAppBanner({ title, body });
}
);
return () => subscription.remove();
}, []);addNotificationResponseReceivedListener
Notifications.addNotificationResponseReceivedListener fires when the user taps a notification, regardless of whether the app was in the background or killed. The listener receives a response object that contains the notification, the action identifier (which button was tapped), and any user text input.
Use this to navigate to the relevant screen based on the notification's data payload. This is the most important notification handler because it drives the deep navigation behavior users expect when tapping a notification.
useEffect(() => {
const subscription = Notifications.addNotificationResponseReceivedListener(
(response) => {
const { data } = response.notification.request.content;
console.log('User tapped notification:', data);
if (data.screen) {
navigation.navigate(data.screen, { id: data.id });
}
}
);
return () => subscription.remove();
}, []);Notification Data Payload Design
The data field in a push notification is your app's contract with itself — it determines what happens when the notification is tapped. Design a consistent schema that includes the destination screen name and all parameters that screen needs.
A well-designed data payload allows any notification to navigate to precisely the right screen with the right content without any guessing. Use type-safe constants for action types to prevent typos causing silent navigation failures.
// Consistent data payload schema:
const notificationData = {
type: 'new_message', // action type
screen: 'Chat', // destination screen name
conversationId: 'abc', // screen params
senderId: '123',
};
// Response handler:
const { type, screen, conversationId } = response.notification.request.content.data;
switch (type) {
case 'new_message':
navigation.navigate(screen, { conversationId });
break;
case 'order_update':
navigation.navigate('OrderDetail', { orderId: data.orderId });
break;
}Foreground Notification Display Control
By default in expo-notifications, notifications received while the app is in the foreground are silent (no banner, no sound). Control this with the setNotificationHandler set at app startup. The handler function is async — you can even make an API call to decide whether to show a notification based on user preferences.
Return shouldShowAlert: true to show the system banner even when the app is open. This is appropriate for notifications from other users (messages) but often not for your own app's activity notifications.
Notifications.setNotificationHandler({
handleNotification: async (notification) => {
const { type } = notification.request.content.data;
// Show banner for messages but not for own activity:
return {
shouldShowAlert: type !== 'own_activity',
shouldPlaySound: type === 'new_message',
shouldSetBadge: true,
};
},
});Background Notification Handling on iOS
On iOS, you can configure background notifications (silent push notifications) that wake the app in the background to fetch data without showing a banner. Set content-available: 1 in the APNs payload. The app gets a short window (~30 seconds) to fetch data.
Background fetch is useful for pre-loading content before the user opens the app from a notification, ensuring the screen is ready instantly. Handle it with expo-notifications' background notification tasks using Expo's task manager.
import * as TaskManager from 'expo-task-manager';
import * as Notifications from 'expo-notifications';
const BACKGROUND_NOTIFICATION_TASK = 'background-notification';
TaskManager.defineTask(BACKGROUND_NOTIFICATION_TASK,
async ({ data: { notification }, error }) => {
if (error) return;
// Fetch fresh data silently in the background:
await prefetchDataForNotification(notification.request.content.data);
}
);
Notifications.registerTaskAsync(BACKGROUND_NOTIFICATION_TASK);Notification Action Buttons
Notifications can include action buttons that let users respond without opening the app. For example, a message notification might have 'Reply' and 'Mark Read' buttons. Configure categories with Notifications.setNotificationCategoryAsync and reference the category in your push payload.
The tap response listener's response.actionIdentifier tells you which button was tapped. For text input actions, response.userText contains what the user typed directly from the notification.
// Define notification category with actions:
await Notifications.setNotificationCategoryAsync('message', [
{
identifier: 'reply',
buttonTitle: 'Reply',
textInput: { submitButtonTitle: 'Send', placeholder: 'Type a reply...' },
},
{
identifier: 'mark_read',
buttonTitle: 'Mark as Read',
isDestructive: false,
},
]);
// In response listener:
if (response.actionIdentifier === 'reply') {
sendReply(response.userText, messageId);
}Managing Badge Count
The badge count is the red number on your iOS app icon. Set it by including a badge number in your push payload, or update it from within the app using Notifications.setBadgeCountAsync(count). Reduce the badge when the user reads notifications or visits the relevant screen.
A common pattern: server sets badge to unread count when sending a push, and app calls setBadgeCountAsync(0) when the user opens the inbox. Always fetch the true unread count from your server rather than incrementing a local counter, since multiple devices must stay in sync.
import * as Notifications from 'expo-notifications';
// Clear badge when user opens inbox:
async function clearBadge() {
await Notifications.setBadgeCountAsync(0);
}
// Get current badge count:
const count = await Notifications.getBadgeCountAsync();
console.log('Current badge:', count);
// Update badge from server-returned unread count:
async function updateBadge(unreadCount) {
await Notifications.setBadgeCountAsync(unreadCount);
}Dismissing Displayed Notifications
After reading a notification in-app, you should dismiss the corresponding notification from the notification center so it doesn't mislead the user. Use Notifications.dismissNotificationAsync(identifier) for a specific notification or Notifications.dismissAllNotificationsAsync() to clear all.
Call dismiss in the notification response handler after navigating to the relevant screen, or in useEffect on the target screen when it mounts. The notification identifier is available in the response object.
const subscription = Notifications.addNotificationResponseReceivedListener(
async (response) => {
const { data } = response.notification.request.content;
const notifId = response.notification.request.identifier;
// Navigate to relevant screen:
navigation.navigate(data.screen, { id: data.id });
// Dismiss the notification from notification center:
await Notifications.dismissNotificationAsync(notifId);
}
);Getting All Pending Notifications
Retrieve all currently displayed notifications in the notification center with Notifications.getPresentedNotificationsAsync(). Use this on app launch to handle any notifications the user hasn't tapped yet, or to display an unread count badge based on actual notification center contents.
On app foreground, you can also loop through pending notifications and dismiss ones that are now stale (e.g., expired promotions or events that have passed).
useEffect(() => {
// When app comes to foreground:
async function cleanupStaleNotifications() {
const displayed = await Notifications.getPresentedNotificationsAsync();
const now = Date.now();
for (const notif of displayed) {
const { expiresAt } = notif.request.content.data;
if (expiresAt && expiresAt < now) {
await Notifications.dismissNotificationAsync(notif.request.identifier);
}
}
}
cleanupStaleNotifications();
}, [appState]);A Complete Notification Handler Setup
A production-ready notification setup combines all the pieces: set the handler at startup, register listeners in a custom hook, and wire them to navigation. The custom hook handles both foreground (show banner, update state) and tap responses (navigate), and always cleans up listeners on unmount.
This architecture keeps notification logic centralized, testable, and separate from individual screen components.
function useNotifications(navigation) {
useEffect(() => {
const received = Notifications.addNotificationReceivedListener(
(notif) => handleForeground(notif)
);
const response = Notifications.addNotificationResponseReceivedListener(
(resp) => handleTap(resp, navigation)
);
return () => {
received.remove();
response.remove();
};
}, [navigation]);
}
// Use in root component:
const navigation = useNavigation();
useNotifications(navigation);Quick Check
Test your understanding of React Native Mobile Development concepts from this lesson.
Lesson Recap
In this lesson you learned: addNotificationReceivedListener handles notifications arriving while the app is in the foreground, addNotificationResponseReceivedListener handles user taps on notifications from any app state and should navigate to the relevant screen, and action buttons with categories enable users to reply or take actions directly from the notification without opening the app. Next up we configure notification channels and add rich content like images and action buttons.
常见问题解答
「处理前台与后台通知」课时是免费的吗？
是的 — 「处理前台与后台通知」的完整文本可在网页上免费阅读。要进行交互式练习（内置代码编辑器和全天候 AI 导师）并解锁 React Native Academy 课程的其余内容，请升级到 CoddyKit PRO。 React Native Academy 课程共包含 4 节课。
「处理前台与后台通知」这节课中我会学到什么？
使用 addNotificationReceivedListener 处理应用打开时收到的通知，并使用 addNotificationResponseReceivedListener 响应用户点击通知的操作。 你通过在浏览器中直接运行的动手代码来练习 React Native Academy，全天候 AI 导师会在你学习这节课的过程中回答你的问题。
学习 React Native Academy 需要有经验吗？
无需任何先前经验。CoddyKit 上的 React Native Academy 课程适合初学者到高级学习者，你可以从这里开始或从头开始，按照自己的节奏学习。 这是第 3 节课，共 4 节。
「处理前台与后台通知」课时需要多长时间？
大多数 CoddyKit 课程大约需要 5–10 分钟。每节课都很精短且互动，所以你能稳步进步，并在网页和应用中从离开的地方继续。
我能在这节 React Native Academy 课中编写并运行代码吗？
能。每节 React Native Academy 课都包含内置代码编辑器，你可以在浏览器中直接编写并运行真实代码，并获得即时 AI 反馈 — 无需本地设置。