การตั้งเวลาการแจ้งเตือนภายในเครื่อง

Local notifications are alerts that your app schedules and delivers entirely on-device, without a server. Unlike push notifications, they do not require an internet connection or a backend service. They are ideal for reminders, daily habit prompts, timer alerts, and in-app alerts that trigger after a specific time or based on a recurring schedule.

Install expo-notifications using the Expo install command so the SDK-compatible version is selected. In managed Expo projects native linking is automatic. Also add the notification configuration block to app.json to set the Android notification icon and color used by the OS.

On both iOS and Android you must request notification permission before scheduling any notification. iOS requires explicit user approval — the system shows a dialog. Android 13+ also requires runtime permission. Call Notifications.requestPermissionsAsync() and check whether status is 'granted' before proceeding.

Set a global notification handler with Notifications.setNotificationHandler to control how notifications behave when the app is in the foreground. Without this, notifications delivered while your app is open are silently ignored on iOS. Call it once at the module level (outside any component) so it is always active.

Notifications.scheduleNotificationAsync schedules a notification to be delivered at a specific time. The trigger can be a number of seconds from now, a specific Date object, or a repeating calendar trigger. The function returns a unique notification identifier that you can use later to cancel the notification if needed.

To schedule a repeating notification — for example a daily 8 AM reminder — use a calendar trigger with a repeats: true flag. Specify the hour, minute, and optionally day-of-week to create any recurring pattern. The OS delivers the notification at the specified time and automatically reschedules it for the next occurrence.

Save the notification identifier returned by scheduleNotificationAsync (e.g., in state or AsyncStorage) so you can cancel it later. Call Notifications.cancelScheduledNotificationAsync(id) with the saved ID to cancel a specific notification. Use cancelAllScheduledNotificationsAsync() to cancel all pending notifications at once.

Use Notifications.addNotificationReceivedListener to react when a notification arrives while the app is open. This is useful for updating in-app badges, playing a custom sound, or refreshing a data feed. Always remove the listener in the useEffect cleanup to prevent memory leaks.

Use Notifications.addNotificationResponseReceivedListener to handle when the user taps a notification banner. This callback fires whether the app was in the foreground, background, or closed. Use the custom data field you attached when scheduling to navigate to the correct screen in your app.

Call Notifications.getAllScheduledNotificationsAsync() to retrieve a list of all pending scheduled notifications. This is useful for debugging, for showing a 'Reminders' management screen where users can review and delete scheduled notifications, or for preventing duplicate scheduling if the user reopens the settings screen.

On iOS, set the app badge number with Notifications.setBadgeCountAsync(count). On Android 8+, notifications must be assigned to a notification channel which controls sound, vibration, and importance. Create a channel once on app startup using Notifications.setNotificationChannelAsync and reference its ID in your notification's channelId field.

Test your understanding of React Native Mobile Development concepts from this lesson.

In this lesson you learned: requestPermissionsAsync must be granted before any notification can appear, scheduleNotificationAsync with a trigger delivers one-time or repeating notifications at specified times, and addNotificationResponseReceivedListener handles user taps to navigate to the right screen. Next up we explore handling permissions gracefully.