Solution

1. Update AndroidManifest.xml

Add the required permission and queries to your android/app/src/main/AndroidManifest.xml:

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="your.package.name">
    
    <!-- Add this permission -->
    <uses-permission android:name="android.permission.REQUEST_INSTALL_PACKAGES" />
    
    <!-- Add queries for package installer -->
    <queries>
        <intent>
            <action android:name="android.intent.action.VIEW" />
            <data android:scheme="package" />
        </intent>
    </queries>
    
    <application>
        <!-- ... rest of your manifest ... -->
    </application>
</manifest>

2. Proper Permission Handling

import 'package:permission_handler/permission_handler.dart';

Future<bool> requestInstallPermission() async {
  try {
    // Check current status
    final status = await Permission.requestInstallPackages.status;
    
    if (status.isDenied) {
      // Request permission
      final result = await Permission.requestInstallPackages.request();
      return result.isGranted;
    }
    
    return status.isGranted;
  } catch (e) {
    print('Error requesting install permission: $e');
    return false;
  }
}

// Usage example
void installApp() async {
  final hasPermission = await requestInstallPermission();
  
  if (hasPermission) {
    // Proceed with installation
    // Your installation code here
  } else {
    // Handle permission denied
    showPermissionDeniedDialog();
  }
}

3. Activity Result Handling

Update your MainActivity.kt (Kotlin) or MainActivity.java (Java):

// Kotlin
package your.package.name

import io.flutter.embedding.android.FlutterActivity
import io.flutter.embedding.engine.FlutterEngine
import io.flutter.plugin.common.MethodChannel

class MainActivity: FlutterActivity() {
    override fun configureFlutterEngine(flutterEngine: FlutterEngine) {
        super.configureFlutterEngine(flutterEngine)
        
        // Add custom result handling if needed
        MethodChannel(flutterEngine.dartExecutor.binaryMessenger, "install_channel")
            .setMethodCallHandler { call, result ->
                when (call.method) {
                    "checkInstallPermission" -> {
                        // Your custom permission check logic
                        result.success(true)
                    }
                    else -> result.notImplemented()
                }
            }
    }
    
    override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
        super.onActivityResult(requestCode, resultCode, data)
        // Add custom result handling if needed
    }
}

4. Complete Example with Error Handling

import 'package:flutter/material.dart';
import 'package:permission_handler/permission_handler.dart';

class InstallPermissionHandler extends StatefulWidget {
  const InstallPermissionHandler({Key? key}) : super(key: key);

  @override
  State<InstallPermissionHandler> createState() => _InstallPermissionHandlerState();
}

class _InstallPermissionHandlerState extends State<InstallPermissionHandler> {
  PermissionStatus _permissionStatus = PermissionStatus.denied;

  @override
  void initState() {
    super.initState();
    _checkPermission();
  }

  Future<void> _checkPermission() async {
    try {
      final status = await Permission.requestInstallPackages.status;
      setState(() {
        _permissionStatus = status;
      });
    } catch (e) {
      print('Error checking permission: $e');
    }
  }

  Future<void> _requestPermission() async {
    try {
      final status = await Permission.requestInstallPackages.request();
      setState(() {
        _permissionStatus = status;
      });
    } catch (e) {
      print('Error requesting permission: $e');
      // Show error dialog
      showDialog(
        context: context,
        builder: (context) => AlertDialog(
          title: const Text('Error'),
          content: Text('Failed to request permission: $e'),
          actions: [
            TextButton(
              onPressed: () => Navigator.pop(context),
              child: const Text('OK'),
            ),
          ],
        ),
      );
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('Install Permission')),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: [
            Text('Permission status: $_permissionStatus'),
            const SizedBox(height: 16),
            ElevatedButton(
              onPressed: _requestPermission,
              child: const Text('Request Permission'),
            ),
          ],
        ),
      ),
    );
  }
}

Additional Configuration

1. Gradle Settings

Update your android/app/build.gradle:

android {
    defaultConfig {
        // Minimum SDK version should be 23 or higher
        minSdkVersion 23
        
        // Other config...
    }
}

2. ProGuard Rules (if using ProGuard)

Add to android/app/proguard-rules.pro:

-keep class com.baseflow.permissionhandler.** { *; }

Common Issues and Solutions

1. App Crashes on Return

If the app still crashes when returning from the permission dialog:

// Wrap permission request in try-catch
Future<void> safeRequestPermission() async {
  try {
    await Permission.requestInstallPackages.request();
  } catch (e) {
    // Handle error gracefully
    print('Permission request failed: $e');
    // Optionally restart app or show error
  }
}

2. Permission Not Showing

Ensure your manifest has the correct permission:

<uses-permission android:name="android.permission.REQUEST_INSTALL_PACKAGES" />

3. Android 13+ Issues

For Android 13 (API 33) and above, add:

<uses-permission android:name="android.permission.POST_NOTIFICATIONS" />

Best Practices

1. Check Permission Before Requesting

if (await Permission.requestInstallPackages.isDenied) {
  // Request permission
}

2. Handle Permanent Denial

if (await Permission.requestInstallPackages.isPermanentlyDenied) {
  // Open app settings
  openAppSettings();
}

3. Graceful Degradation

void handleInstallation() async {
  if (!await requestInstallPermission()) {
    // Provide alternative solution
    showAlternativeDialog();
  }
}

Remember to:

• Handle all possible permission states
• Provide clear user feedback
• Implement proper error handling
• Test on multiple Android versions
• Consider platform-specific behavior

Would you like me to explain any part in more detail?