Flutter开发笔记18 - iOS通过FlutterEventChannel发送消息给Flutter

主要逻辑：

1. Flutter端 EventChannel监听Native传来的消息
2. Native通过创建EventChannel，给Flutter层发送消息

代码梳理

1、Flutter端创建EventChannel进行监听

import 'dart:async';

import 'package:flutter/services.dart';

class FlutterJlBluetoothPlugin {

  // 工厂模式
  factory FlutterJlBluetoothPlugin() =>_getInstance();
  static FlutterJlBluetoothPlugin get instance => _getInstance();
  static FlutterJlBluetoothPlugin? _instance;
  MethodChannel _methodChannel;
  EventChannel _eventChannel;
  FlutterJlBluetoothPlugin._internal(this._methodChannel, this._eventChannel) {
    _eventChannel.receiveBroadcastStream().listen(_onEvent, onError: _onError);
  }

  static FlutterJlBluetoothPlugin _getInstance() {
    if (_instance == null) {
      MethodChannel methodChannel = MethodChannel('flutter_jl_bluetooth_plugin');
      EventChannel eventChannel = EventChannel('flutter_jl_bluetooth_plugin_event');
      _instance = new FlutterJlBluetoothPlugin._internal(methodChannel, eventChannel);
    }
    return _instance!;
  }

  /// 获取版本方法
  Future get platformVersion async {
    final String version =
    await _methodChannel.invokeMethod('getPlatformVersion');
    return version;
  }

  /// 数据接收
  static void _onEvent(dynamic value) {
    print("flutter_jl_bluetooth_plugin_event _onEvent: $value");
  }
  /// 数据接收: 错误处理
  static void _onError(dynamic value) {
    print("flutter_jl_bluetooth_plugin_event _onError: $value");
  }

}

说明：对于receiveBroadcastStream建议添加名称作为native中传递数据的参数使用

2、iOS端通过Event向Flutter发送数据

2.1 初始化与实现 FlutterStreamHandler的代理方法

#import "FlutterJlBluetoothPlugin.h"
#import "MJExtension.h"

@interface FlutterJlBluetoothPlugin() 

@property (nonatomic, strong) FlutterEventSink eventSink;

@end

@implementation FlutterJlBluetoothPlugin

+ (instancetype)sharedInstance {
    static FlutterJlBluetoothPlugin *instance = nil;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{
        instance = [[self alloc] init];
    });
    return instance;
}

+ (void)registerWithRegistrar:(NSObject*)registrar {
    FlutterMethodChannel *channel = [FlutterMethodChannel methodChannelWithName:@"flutter_jl_bluetooth_plugin" binaryMessenger:[registrar messenger]];
    FlutterJlBluetoothPlugin *instance = [FlutterJlBluetoothPlugin sharedInstance];
    [registrar addMethodCallDelegate:instance channel:channel];
    
    FlutterEventChannel *eventChannel = [FlutterEventChannel eventChannelWithName:@"flutter_jl_bluetooth_plugin_event" binaryMessenger:[registrar messenger]];
    [eventChannel setStreamHandler:instance];
}

- (void)handleMethodCall:(FlutterMethodCall*)call result:(FlutterResult)result {
    if ([@"getPlatformVersion" isEqualToString:call.method]) {
        result([@"iOS " stringByAppendingString:[[UIDevice currentDevice] systemVersion]]);
    } else {
        result(FlutterMethodNotImplemented);
    }
}

#pragma mark - FlutterStreamHandler

- (FlutterError* _Nullable)onListenWithArguments:(id _Nullable)arguments eventSink:(FlutterEventSink)eventSink {
    self.eventSink = eventSink;
    return nil;
}
 
- (FlutterError* _Nullable)onCancelWithArguments:(id _Nullable)arguments {
    self.eventSink = nil;
    return nil;
}


@end

2.2 最后是native端调用

if (self.eventSink) self.eventSink([NSDictionary new]);