Auf Geräte-APIs zugreifen: Kamera, Standort und Push-Benachrichtigungen

Expo-SDK-Module

# Install what you need:
npx expo install expo-camera expo-location expo-notifications

Berechtigungen anfordern

import * as Location from 'expo-location';

async function getLocation() {
  const { status } = await Location.requestForegroundPermissionsAsync();
  if (status !== 'granted') {
    Alert.alert('Permission denied');
    return;
  }
  const location = await Location.getCurrentPositionAsync({});
  console.log(location.coords);
}

Kamerazugriff

import { CameraView, useCameraPermissions } from 'expo-camera';
import { useRef } from 'react';

export function CameraScreen() {
  const [permission, requestPermission] = useCameraPermissions();
  const cameraRef = useRef(null);

  if (!permission?.granted) {
    return <Button onPress={requestPermission} title="Grant camera" />;
  }

  const takePicture = async () => {
    const photo = await cameraRef.current?.takePictureAsync();
    console.log(photo?.uri);
  };

  return <CameraView ref={cameraRef} facing="back" />;
}

Bildauswahl

import * as ImagePicker from 'expo-image-picker';

async function pickImage() {
  const result = await ImagePicker.launchImageLibraryAsync({
    mediaTypes: ImagePicker.MediaTypeOptions.Images,
    quality: 0.8,
    allowsEditing: true,
    aspect: [4, 3],
  });

  if (!result.canceled) {
    console.log(result.assets[0].uri);
  }
}

Standortverfolgung

useEffect(() => {
  let subscription;
  (async () => {
    const { status } = await Location.requestForegroundPermissionsAsync();
    if (status !== 'granted') return;
    subscription = await Location.watchPositionAsync(
      { accuracy: Location.Accuracy.High, distanceInterval: 10 },
      location => setCoords(location.coords)
    );
  })();
  return () => subscription?.remove();
}, []);

Geokodierung und Reverse-Geokodierung

const [address] = await Location.reverseGeocodeAsync({ latitude: 37.78, longitude: -122.43 });
console.log(`${address.street}, ${address.city}, ${address.country}`);

Einrichtung von Push-Benachrichtigungen

import * as Notifications from 'expo-notifications';

async function registerForPushNotifications() {
  const { status } = await Notifications.requestPermissionsAsync();
  if (status !== 'granted') return null;
  const token = (await Notifications.getExpoPushTokenAsync()).data;
  return token; // send this to your server
}

Eingehende Benachrichtigungen verarbeiten

useEffect(() => {
  const receivedSub = Notifications.addNotificationReceivedListener(notification => {
    console.log('Received:', notification);
  });
  const responseSub = Notifications.addNotificationResponseReceivedListener(response => {
    const data = response.notification.request.content.data;
    router.push(`/post/${data.postId}`);
  });
  return () => { receivedSub.remove(); responseSub.remove(); };
}, []);

Lokale Benachrichtigungen

await Notifications.scheduleNotificationAsync({
  content: { title: 'Reminder', body: 'Check your app!', data: {} },
  trigger: { seconds: 60 }, // fires after 60 seconds
});

Standort im Hintergrund

Schnelltest

Zusammenfassung