flutter_native_bridge 1.0.0

Zero-boilerplate bridge between Flutter and native platforms. Call native Kotlin/Swift methods from Dart with minimal setup - just annotate and call!

Flutter Native Bridge

Zero-boilerplate bridge between Flutter and native platforms. Call native Kotlin/Swift methods from Dart with minimal setup.

Features

• Cross-Platform - Supports both Android (Kotlin) and iOS (Swift)
• Minimal Setup - Just add annotations and one line of registration
• Auto-Discovery - Automatically finds and registers annotated classes
• Type-Safe - Generated Dart code with full type support
• IDE Autocomplete - Works seamlessly with your IDE
• No Native Dependencies - No KSP or annotation processors needed
• Flexible - Use code generation or runtime calls

Installation

Add to your pubspec.yaml:

dependencies:
  flutter_native_bridge: ^1.0.0

Quick Start

Android (Kotlin)

1. Annotate Your Kotlin Code

// Option A: Expose all methods with @NativeBridge
@NativeBridge
class DeviceService {
    fun getModel(): String = Build.MODEL
    fun getVersion(): Int = Build.VERSION.SDK_INT

    @NativeIgnore  // Exclude specific methods
    fun internalMethod() { }
}

// Option B: Expose specific methods with @NativeFunction
class MainActivity : FlutterActivity() {
    @NativeFunction
    fun greet(name: String): String = "Hello, $name!"
}

2. Register in MainActivity

import io.nativebridge.FlutterNativeBridge

class MainActivity : FlutterActivity() {
    override fun configureFlutterEngine(flutterEngine: FlutterEngine) {
        super.configureFlutterEngine(flutterEngine)
        FlutterNativeBridge.register(this)  // One line does it all!
    }
}

iOS (Swift)

1. Create Your Swift Classes

import Foundation

// Inherit from NSObject and use @objc to expose methods
class DeviceService: NSObject {
    @objc func getModel() -> String {
        return UIDevice.current.model
    }

    @objc func getVersion() -> String {
        return UIDevice.current.systemVersion
    }
}

2. Register in AppDelegate

import flutter_native_bridge

@UIApplicationMain
@objc class AppDelegate: FlutterAppDelegate {
    override func application(
        _ application: UIApplication,
        didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?
    ) -> Bool {
        GeneratedPluginRegistrant.register(with: self)

        // Register your native classes
        FlutterNativeBridge.register(DeviceService())

        return super.application(application, didFinishLaunchingWithOptions: launchOptions)
    }
}

Generate Dart Code

dart run flutter_native_bridge:generate

This scans both Android and iOS source files and creates lib/native_bridge.g.dart.

Use in Dart

import 'native_bridge.g.dart';

// Type-safe calls with autocomplete - works on both platforms!
final model = await DeviceService.getModel();
final version = await DeviceService.getVersion();

Platform Comparison

Feature	Android	iOS
Class annotation	@NativeBridge	Inherit NSObject
Method annotation	@NativeFunction	@objc
Exclude method	@NativeIgnore	Don't add @objc
Registration	FlutterNativeBridge.register(this)	FlutterNativeBridge.register(obj)

Android Annotations

Annotation	Target	Description
@NativeBridge	Class	Exposes all public methods to Flutter
@NativeFunction	Method	Exposes a single method to Flutter
@NativeIgnore	Method	Excludes a method (use with @NativeBridge)

iOS Requirements

• Classes must inherit from NSObject
• Methods must be marked with @objc
• Return types must be Objective-C compatible

Auto-Discovery (Android)

When you call FlutterNativeBridge.register(this) on Android, the plugin automatically:

1. Registers the activity if it has @NativeFunction methods
2. Scans your package for classes with @NativeBridge or @NativeFunction
3. Creates instances using available constructors:
   • Activity parameter
   • Context parameter
   • No-arg constructor

Runtime API (Without Code Generation)

You can also call methods at runtime without generating code:

import 'package:flutter_native_bridge/flutter_native_bridge.dart';

// Direct call
final model = await FlutterNativeBridge.call<String>('DeviceService', 'getModel');

// Using bridge instance
final device = NativeBridge('DeviceService');
final model = await device.call<String>('getModel');

// Discover registered classes
final classes = await FlutterNativeBridge.discover();
// {'DeviceService': ['getModel', 'getVersion']}

Supported Types

Kotlin Type	Swift Type	Dart Type
String	String	String
Int	Int	int
Long	Int64	int
Double	Double	double
Float	Float	double
Boolean	Bool	bool
List<T>	[T]	List<T>
Map<K, V>	[K: V]	Map<K, V>

Complete Example

Android (Kotlin)

// android/app/src/main/kotlin/.../MainActivity.kt
package com.example.myapp

import io.nativebridge.FlutterNativeBridge
import io.nativebridge.NativeBridge
import io.nativebridge.NativeFunction

@NativeBridge
class DeviceService {
    fun getDeviceModel(): String = Build.MODEL
    fun getAndroidVersion(): Int = Build.VERSION.SDK_INT
}

class MainActivity : FlutterActivity() {
    override fun configureFlutterEngine(flutterEngine: FlutterEngine) {
        super.configureFlutterEngine(flutterEngine)
        FlutterNativeBridge.register(this)
    }

    @NativeFunction
    fun greet(name: String): String = "Hello, $name from Android!"
}

iOS (Swift)

// ios/Runner/DeviceService.swift
import Foundation
import UIKit

class DeviceService: NSObject {
    @objc func getDeviceModel() -> String {
        return UIDevice.current.model
    }

    @objc func getIOSVersion() -> String {
        return UIDevice.current.systemVersion
    }
}

// ios/Runner/AppDelegate.swift
import flutter_native_bridge

@UIApplicationMain
@objc class AppDelegate: FlutterAppDelegate {
    override func application(
        _ application: UIApplication,
        didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?
    ) -> Bool {
        GeneratedPluginRegistrant.register(with: self)
        FlutterNativeBridge.register(DeviceService())
        return super.application(application, didFinishLaunchingWithOptions: launchOptions)
    }
}

Dart

// lib/main.dart
import 'native_bridge.g.dart';

void main() async {
  final model = await DeviceService.getDeviceModel();
  print('Device: $model');
}

Troubleshooting

Android: Auto-discovery not working?

Use manual registration:

FlutterNativeBridge.registerObjects(DeviceService(), OtherService())

Android: Method not found?

Ensure the method is:

• Public (not private or internal)
• Annotated with @NativeFunction (if class doesn't have @NativeBridge)
• Not annotated with @NativeIgnore

iOS: Method not found?

Ensure:

• Class inherits from NSObject
• Method is marked with @objc
• Return type is Objective-C compatible

Name conflicts?

If you have classes with the same name on both platforms or from different packages:

// Android
FlutterNativeBridge.register("AndroidDevice", DeviceService())

// iOS
FlutterNativeBridge.register(name: "iOSDevice", object: DeviceService())

License

MIT License - see LICENSE for details.