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. This is 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, and your progress syncs across the web and the CoddyKit app. The Flutter Mobile Development course includes 4 lessons in total.
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. 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. The Flutter Mobile Development course includes 4 lessons in total.
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, so you can start here or from the beginning and move at your own pace. This is lesson 4 of 4.
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