Permissions handling in Flutter - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import the permissions package in Flutter.

Flutter

import '[1]';

Drag options to blanks, or click blank then click option'

Apackage:flutter/material.dart

Bpackage:flutter/widgets.dart

Cpackage:flutter/services.dart

Dpackage:permission_handler/permission_handler.dart

Attempts:

3 left

💡 Hint

Common Mistakes

Importing core Flutter packages instead of the permissions package.

Forgetting to add the permission_handler package to pubspec.yaml.

To handle permissions in Flutter, you need to import the permission_handler package.

2fill in blank

medium

Complete the code to request camera permission using permission_handler.

Flutter

var status = await Permission.[1].request();

Drag options to blanks, or click blank then click option'

Alocation

Bcamera

Cstorage

Dmicrophone

Attempts:

3 left

💡 Hint

Common Mistakes

Requesting the wrong permission type.

Not awaiting the request call.

To request camera permission, use Permission.camera.request().

3fill in blank

hard

Fix the error in checking if permission is granted.

Flutter

if (await Permission.[1].isGranted) {
  print('Permission granted');
}

Drag options to blanks, or click blank then click option'

Acamera

Brequest

Cstatus

Dcheck

Attempts:

3 left

💡 Hint

Common Mistakes

Using method names like 'request' or 'check' instead of permission types.

Not awaiting the isGranted call.

You check if a specific permission like camera is granted by calling Permission.camera.isGranted.

4fill in blank

hard

Fill both blanks to check and request microphone permission if not granted.

Flutter

if (!await Permission.[1].[2]) {
  await Permission.microphone.request();
}

Drag options to blanks, or click blank then click option'

Amicrophone

BisDenied

CisGranted

DisRestricted

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'isDenied' or 'isRestricted' instead of 'isGranted' for checking permission.

Checking a different permission than microphone.

You check if the microphone permission is granted by Permission.microphone.isGranted. If not granted, you request it.

5fill in blank

hard

Fill all three blanks to create a map of permissions and their statuses filtering only granted ones.

Flutter

var grantedPermissions = {
  [1]: [2] for [3] in permissions
  if ([2].isGranted)
};

Drag options to blanks, or click blank then click option'

Aperm

Bstatus

Dpermissions

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing variable names or using the same name for different roles.

Not filtering permissions correctly.

This code loops over permissions with variable perm, gets status for each, and keeps only those where status.isGranted is true.

Practice

1. What is the main purpose of handling permissions in a Flutter app?

easy

A. To create animations for UI elements

B. To safely access sensitive device features like camera or location

C. To change the app's theme dynamically

D. To improve app performance by caching data

Solution

1. Step 1: Understand app permissions

   Permissions allow apps to access sensitive features like camera, microphone, or location safely.

2. Step 2: Identify the purpose in Flutter apps

   Handling permissions ensures the app asks user consent before accessing these features.

3. Final Answer:

   To safely access sensitive device features like camera or location -> Option B

4. Quick Check:

   Permissions = Safe access to sensitive features [OK]

Hint: Permissions control access to device features safely [OK]

Common Mistakes:

• Confusing permissions with UI customization
• Thinking permissions improve performance
• Assuming permissions are for animations

2. Which Flutter package is commonly used to check and request permissions?

easy

A. http

B. provider

C. permission_handler

D. shared_preferences

Solution

1. Step 1: Identify permission packages

   The permission_handler package is designed to manage permissions in Flutter.

2. Step 2: Exclude unrelated packages

   http is for network calls, provider for state management, and shared_preferences for local storage.

3. Final Answer:

   permission_handler -> Option C

4. Quick Check:

   Permission package = permission_handler [OK]

Hint: permission_handler manages permissions in Flutter [OK]

Common Mistakes:

• Choosing http for permissions
• Confusing provider with permission handling
• Using shared_preferences for permissions

3. What will the following Flutter code print if the camera permission is granted?

var status = await Permission.camera.status;
if (status.isGranted) {
  print('Camera permission granted');
} else {
  print('Camera permission denied');
}

medium

A. Syntax error

B. Camera permission denied

C. Permission status unknown

D. Camera permission granted

Solution

1. Step 1: Check permission status

   The code checks if camera permission is granted using status.isGranted.

2. Step 2: Determine output for granted permission

   If granted, it prints 'Camera permission granted'. Otherwise, it prints denial message.

3. Final Answer:

   Camera permission granted -> Option D

4. Quick Check:

   Granted permission prints granted message [OK]

Hint: isGranted true means permission granted [OK]

Common Mistakes:

• Confusing isGranted with isDenied
• Expecting syntax error
• Ignoring async await usage

4. Identify the error in this Flutter code snippet for requesting location permission:

var status = await Permission.location.request();
if (status == PermissionStatus.granted) {
  print('Permission granted');
} else {
  print('Permission denied');
}

medium

A. No error, code is correct

B. Using == to compare PermissionStatus instead of isGranted property

C. Permission.location.request() does not exist

D. Missing await keyword before request()

Solution

1. Step 1: Review permission request syntax

   The request() method returns a PermissionStatus which can be compared using ==.

2. Step 2: Confirm code correctness

   The code correctly awaits the request and compares status to PermissionStatus.granted.

3. Final Answer:

   No error, code is correct -> Option A

4. Quick Check:

   Permission request syntax is correct [OK]

Hint: PermissionStatus can be compared with == safely [OK]

Common Mistakes:

• Thinking isGranted must be used instead of ==
• Forgetting await before request()
• Assuming request() method does not exist

5. You want to show a message to the user only if the app has both camera and microphone permissions granted. Which Flutter code snippet correctly checks this using permission_handler?

hard

A. if (await Permission.camera.isGranted && await Permission.microphone.isGranted) {
print('All permissions granted');
}

B. if (await Permission.camera.request() && await Permission.microphone.request()) {
print('All permissions granted');
}

C. if (Permission.camera.isGranted && Permission.microphone.isGranted) {
print('All permissions granted');
}

D. if (Permission.camera.status.isGranted && Permission.microphone.status.isGranted) {
print('All permissions granted');
}

Solution

1. Step 1: Understand async permission checks

   Checking isGranted requires awaiting because it returns a Future<bool>.

2. Step 2: Analyze each option

   if (await Permission.camera.isGranted && await Permission.microphone.isGranted) { print('All permissions granted'); } correctly awaits both permissions' isGranted properties. if (await Permission.camera.request() && await Permission.microphone.request()) { print('All permissions granted'); } incorrectly awaits request() which returns PermissionStatus, not bool. if (Permission.camera.isGranted && Permission.microphone.isGranted) { print('All permissions granted'); } misses await, causing errors. if (Permission.camera.status.isGranted && Permission.microphone.status.isGranted) { print('All permissions granted'); } accesses status without await, which is a Future.

3. Final Answer:

   if (await Permission.camera.isGranted && await Permission.microphone.isGranted) { print('All permissions granted'); } -> Option A

4. Quick Check:

   Await isGranted for correct permission check [OK]

Hint: Await isGranted to check permission status correctly [OK]

Common Mistakes:

• Not awaiting async permission checks
• Using request() instead of isGranted for condition
• Accessing status without await