Akses Hardware: Camera, GPS & Sensors

Salah satu keunggulan utama mobile app dibanding web app adalah akses penuh ke hardware device. Expo menyediakan API yang konsisten untuk camera, location, dan berbagai sensor.

Camera dengan expo-camera

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

export default function CameraScreen() {
  const [permission, requestPermission] = useCameraPermissions();
  const [facing, setFacing] = useState('back');
  const cameraRef = useRef(null);

  if (!permission) return <View />;
  if (!permission.granted) {
    return (
      <View>
        <Text>Butuh izin akses kamera</Text>
        <Pressable onPress={requestPermission}>
          <Text>Grant Permission</Text>
        </Pressable>
      </View>
    );
  }

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

  return (
    <CameraView ref={cameraRef} style={{ flex: 1 }} facing={facing}>
      <Pressable onPress={takePicture}>
        <Text>Take Photo</Text>
      </Pressable>
    </CameraView>
  );
}

Location dengan expo-location

import * as Location from 'expo-location';

async function getCurrentLocation() {
  // Request permission
  const { status } = await Location.requestForegroundPermissionsAsync();
  if (status !== 'granted') {
    alert('Permission denied');
    return;
  }

  // Get current position
  const location = await Location.getCurrentPositionAsync({
    accuracy: Location.Accuracy.High,
  });

  console.log('Latitude:', location.coords.latitude);
  console.log('Longitude:', location.coords.longitude);
  return location;
}

// Watch position (real-time tracking)
const subscription = await Location.watchPositionAsync(
  { accuracy: Location.Accuracy.High, distanceInterval: 10 },
  (location) => {
    console.log('Moved to:', location.coords);
  }
);

// Geocoding (koordinat → alamat)
const address = await Location.reverseGeocodeAsync({
  latitude: -6.2088,
  longitude: 106.8456,
});
console.log(address[0].city); // 'Jakarta'

Sensors

import { Accelerometer, Gyroscope } from 'expo-sensors';

// Accelerometer — deteksi gerakan/guncangan
Accelerometer.setUpdateInterval(100); // ms

const subscription = Accelerometer.addListener(({ x, y, z }) => {
  // Shake detection
  const totalForce = Math.sqrt(x * x + y * y + z * z);
  if (totalForce > 2.5) {
    console.log('Device shaken!');
  }
});

// Cleanup
subscription.remove();

Image Picker

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

async function pickImage() {
  const result = await ImagePicker.launchImageLibraryAsync({
    mediaTypes: ['images'],
    allowsEditing: true,
    aspect: [1, 1],
    quality: 0.8,
  });

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

Permission Pattern

• Selalu request permission sebelum akses hardware — User harus explicitly grant
• Handle denied gracefully — Jelaskan kenapa app butuh permission, arahkan ke Settings
• Foreground vs Background — Location background butuh permission terpisah dan justifikasi ke App Store
• Minimal permission — Hanya minta yang benar-benar dibutuhkan