React Native Academy · Lektion

Lokale Benachrichtigungen planen

Lokale Benachrichtigungen planen ist eine kostenlose React Native Academy-Lektion auf CoddyKit. Dies ist Lektion 3 von 4. Du kannst die komplette Lektion unten kostenlos lesen – dann übst du sie direkt im Browser mit einem integrierten Code-Editor und einem KI-Tutor rund um die Uhr. Sie ist Teil des React Native Academy-Lernpfads, und dein Fortschritt wird über Web und CoddyKit-App synchronisiert. Der React Native Academy-Kurs umfasst insgesamt 4 Lektionen.

Teile dieser Lektion wurden noch nicht übersetzt und werden auf Englisch angezeigt.

What Are Local Notifications?

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.

Installing expo-notifications

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.

npx expo install expo-notifications

// app.json:
{
  "expo": {
    "notification": {
      "icon": "./assets/notification-icon.png",
      "color": "#6200ee",
      "androidMode": "default"
    }
  }
}

Requesting Notification Permission

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.

import * as Notifications from 'expo-notifications';

async function requestNotificationPermission() {
  const { status } = await Notifications.requestPermissionsAsync();
  if (status !== 'granted') {
    Alert.alert(
      'Permission Denied',
      'Enable notifications in Settings to receive reminders.'
    );
    return false;
  }
  return true;
}

Setting a Default Notification Handler

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.

import * as Notifications from 'expo-notifications';

Notifications.setNotificationHandler({
  handleNotification: async () => ({
    shouldShowAlert: true,   // show banner while app is open
    shouldPlaySound: true,
    shouldSetBadge: false,
  }),
});

Scheduling a One-Time Notification

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.

async function scheduleReminder() {
  const hasPermission = await requestNotificationPermission();
  if (!hasPermission) return;

  const id = await Notifications.scheduleNotificationAsync({
    content: {
      title: 'Daily Reminder',
      body: 'Time to check your goals for today!',
      sound: true,
      data: { screen: 'Goals' }, // custom data for handling the tap
    },
    trigger: {
      seconds: 60, // deliver in 60 seconds
    },
  });

  console.log('Notification scheduled with ID:', id);
}

Scheduling a Recurring Notification

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.

await Notifications.scheduleNotificationAsync({
  content: {
    title: 'Good morning!',
    body: 'Your daily coding practice is waiting.',
  },
  trigger: {
    type: Notifications.SchedulableTriggerInputTypes.CALENDAR,
    hour: 8,
    minute: 0,
    repeats: true, // fires every day at 8:00 AM
  },
});

Cancelling a Scheduled Notification

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.

const [notifId, setNotifId] = React.useState<string | null>(null);

async function cancelReminder() {
  if (notifId) {
    await Notifications.cancelScheduledNotificationAsync(notifId);
    setNotifId(null);
    console.log('Notification cancelled');
  }
}

// Or cancel all at once:
await Notifications.cancelAllScheduledNotificationsAsync();

Handling Foreground Notifications

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.

useEffect(() => {
  const subscription = Notifications.addNotificationReceivedListener(
    (notification) => {
      console.log('Received:', notification.request.content.title);
      const screen = notification.request.content.data?.screen;
      if (screen) setBadge(screen);
    }
  );
  return () => subscription.remove();
}, []);

Handling Notification Taps

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.

useEffect(() => {
  const subscription = Notifications.addNotificationResponseReceivedListener(
    (response) => {
      const screen = response.notification.request.content.data?.screen;
      if (screen && navigationRef.current) {
        navigationRef.current.navigate(screen);
      }
    }
  );
  return () => subscription.remove();
}, []);

Getting All Scheduled Notifications

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.

async function listScheduledNotifications() {
  const scheduled = await Notifications.getAllScheduledNotificationsAsync();
  console.log('Pending notifications:', scheduled.length);
  scheduled.forEach((notif) => {
    console.log(
      notif.identifier,
      notif.content.title,
      JSON.stringify(notif.trigger)
    );
  });
}

Badges and Android Channels

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.

if (Platform.OS === 'android') {
  await Notifications.setNotificationChannelAsync('reminders', {
    name: 'Reminders',
    importance: Notifications.AndroidImportance.HIGH,
    vibrationPattern: [0, 250, 250, 250],
    sound: 'default',
  });
}

// Reference in notification:
await Notifications.scheduleNotificationAsync({
  content: { title: 'Reminder', channelId: 'reminders' },
  trigger: { seconds: 30 },
});

Quick Check

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

Lesson Recap

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.

Häufig gestellte Fragen

Ist die Lektion „Lokale Benachrichtigungen planen“ kostenlos?

Ja — der vollständige Text von „Lokale Benachrichtigungen planen“ ist hier im Web kostenlos zu lesen. Um sie interaktiv zu üben (integrierter Code-Editor und 24/7 KI-Tutor) und den Rest des React Native Academy-Kurses freizuschalten, upgrade auf CoddyKit PRO. Der React Native Academy-Kurs umfasst insgesamt 4 Lektionen.

Was lerne ich in „Lokale Benachrichtigungen planen“?

Installieren Sie expo-notifications, fordern Sie die Berechtigung an, planen Sie eine lokale Benachrichtigung mit Verzögerung und behandeln Sie das Antippen der Benachrichtigung, um zu einem bestimmt… Du übst React Native Academy mit praktischem Code, den du direkt im Browser ausführst, und ein 24/7 KI-Tutor beantwortet deine Fragen während du die Lektion bearbeitest.

Brauche ich Erfahrung, um React Native Academy zu starten?

Keine Vorkenntnisse erforderlich. React Native Academy auf CoddyKit ist für Anfänger bis fortgeschrittene Lernende strukturiert, sodass du hier starten oder von Anfang an beginnen und in deinem eigenen Tempo voranschreiten kannst. Dies ist Lektion 3 von 4.

Wie lange dauert die Lektion „Lokale Benachrichtigungen planen“?

Die meisten CoddyKit-Lektionen dauern etwa 5–10 Minuten. Jede ist kompakt und interaktiv, sodass du stetig Fortschritte machst und genau dort weitermachst, wo du aufgehört hast – im Web und in der App.

Kann ich in dieser React Native Academy-Lektion Code schreiben und ausführen?

Ja. Jede React Native Academy-Lektion enthält einen integrierten Code-Editor, sodass du echten Code direkt in deinem Browser schreibst und ausführst und sofort KI-Feedback erhältst — ohne lokale Einrichtung erforderlich.

Alle Lektionen in diesem Kurs

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