Permissions & Sensors
Request runtime permissions and read device sensors like the accelerometer in Flutter to build context-aware, platform-integrated apps.
Permissions & Sensors is a free Flutter Mobile Development lesson on CoddyKit — lesson 4 of 4. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the Flutter Mobile Development learning path, one of 4 lessons in the course, and your progress syncs across the web and the CoddyKit app.
Why Permissions & Sensors?
Many platform features — camera, location, sensors — require runtime permission. And sensors like the accelerometer let your app react to physical movement.
The permission_handler Package
The permission_handler package gives a unified API for requesting and checking permissions across Android and iOS.
dependencies:
permission_handler: ^11.0.0Checking Status
Check whether a permission is granted before using a feature.
final status = await Permission.camera.status;
if (status.isGranted) {
openCamera();
}Requesting a Permission
Call request() to prompt the user. Always handle a denial gracefully.
final result = await Permission.location.request();
if (result.isGranted) {
startTracking();
}Permanently Denied
If the user permanently denies, you cannot re-prompt — send them to settings instead.
if (status.isPermanentlyDenied) {
await openAppSettings();
}Declaring Permissions
You must also declare permissions natively: AndroidManifest.xml on Android and Info.plist usage descriptions on iOS.
<!-- Android -->
<uses-permission android:name="android.permission.CAMERA" />
<!-- iOS Info.plist -->
<key>NSCameraUsageDescription</key>
<string>We need the camera to scan codes</string>Meet the Sensors
The sensors_plus package exposes device motion sensors as streams.
- Accelerometer
- Gyroscope
- Magnetometer
dependencies:
sensors_plus: ^4.0.0Reading the Accelerometer
Subscribe to the accelerometer stream to get x, y, z acceleration values.
accelerometerEventStream().listen((event) {
print('x: ' + event.x.toString() + ' y: ' + event.y.toString());
});The Gyroscope
The gyroscope reports rotation rate around each axis — useful for tilt and orientation effects.
gyroscopeEventStream().listen((event) {
print('rotation: ' + event.x.toString());
});Detecting a Shake
Combine accelerometer axes into a magnitude and compare against a threshold to detect a shake gesture.
import 'dart:math';
void onEvent(AccelerometerEvent e) {
final magnitude = sqrt(e.x * e.x + e.y * e.y + e.z * e.z);
if (magnitude > 15) onShake();
}Cleaning Up Subscriptions
Sensor streams keep firing — cancel the subscription in dispose to save battery.
late StreamSubscription sub;
@override
void dispose() {
sub.cancel();
super.dispose();
}Quick Check
The user permanently denied location. What should your app do?
Recap
You learned permissions and sensors:
- permission_handler: status, request, openAppSettings
- Native declarations on Android and iOS
- sensors_plus accelerometer and gyroscope streams
- Shake detection and cleanup
Your apps can now responsibly access platform capabilities.
Frequently asked questions
Is the “Permissions & Sensors” lesson free?
Yes — the full text of “Permissions & Sensors” is free to read here on the web, and the Flutter Mobile Development course includes 4 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the Flutter Mobile Development course, upgrade to CoddyKit PRO.
What will I learn in “Permissions & Sensors”?
Request runtime permissions and read device sensors like the accelerometer in Flutter to build context-aware, platform-integrated apps. You practise Flutter Mobile Development with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.
Do I need any experience to start Flutter Mobile Development?
No prior experience is required. Flutter Mobile Development on CoddyKit is structured for beginners through advanced learners; this is — lesson 4 of 4, so you can start here or from the beginning and move at your own pace.
How long does the “Permissions & Sensors” lesson take?
Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.
Can I write and run code in this Flutter Mobile Development lesson?
Yes. Every Flutter Mobile Development lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.
All lessons in this course
- Platform Channels (MethodChannel)
- Geolocation & Camera Plugins
- Native UI Integration
- Permissions & Sensors