iOS 主動與native 通訊

flutter與Native交互是必不可少的，今天梳理一下，flutter監聽native消息

大體流程

1. flutter註冊EventChannel
2. flutter EventChannel監聽native消息
3. native經過EventChannel發送消息

代碼梳理

1 flutter Event監聽

const EventChannel("App/Event/Channel", const StandardMethodCodec());

//開始監聽
@override
  void initState() {
    // TODO: implement initState
    super.initState();
    _eventChannel
        .receiveBroadcastStream("init")
        .listen(_onEvent, onError: _onError);
  }

// 數據接收
  void _onEvent(Object value) {
    print(value);
}
// 錯誤處理
  void _onError(dynamic) {}
複製代碼

說明：對於receiveBroadcastStream建議添加名稱做爲native中傳遞數據的參數使用 2 native 經過Event廣播數據 2.1 初始化

FlutterEventChannel *eventChannel = [FlutterEventChannel eventChannelWithName:@"App/Event/Channel" binaryMessenger:flutterViewController];

    [eventChannel setStreamHandler:self];

複製代碼

2.2 數據代理 FlutterStreamHandler

- (FlutterError* _Nullable)onListenWithArguments:(id _Nullable)arguments
                                       eventSink:(FlutterEventSink)events {}//此處的arguments能夠轉化爲剛纔receiveBroadcastStream("init")的名稱，這樣咱們就能夠一個event來監聽多個方法實例
- (FlutterError* _Nullable)onCancelWithArguments:(id _Nullable)arguments {}
複製代碼

傳遞數據實例：

#pragma mark - <FlutterStreamHandler>
// // 這個onListen是Flutter端開始監聽這個channel時的回調，第二個參數 EventSink是用來傳數據的載體。
- (FlutterError* _Nullable)onListenWithArguments:(id _Nullable)arguments
                                       eventSink:(FlutterEventSink)events {
    
    // arguments flutter給native的參數
    // 回調給flutter， 建議使用實例指向，由於該block能夠使用屢次
    if (events) {
        NSMutableDictionary * params = [NSMutableDictionary dictionaryWithCapacity:0];
        [params setValue:mReferNo forKey:@"ataNo"];
        [params setValue:mDocType forKey:@"docType"];
        [params setValue:self.aircraftNo forKey:@"aircraftNo"];
//        [params setValue:[[NetworkingTools networkHeaders]   modelToJSONString] forKey:@"headers"];
//        [params setValue:[NetworkingTools networkHeaders] forKey:@"headers"];
        [params setValue:@"我是標題" forKey:@"title"];
        [params addEntriesFromDictionary:[NetworkingTools networkHeaders] ];
        events([params modelToJSONString]);
    }
    return nil;
}

/// flutter再也不接收
- (FlutterError* _Nullable)onCancelWithArguments:(id _Nullable)arguments {
    // arguments flutter給native的參數
    return nil;
}

複製代碼

最後是native端調用

FlutterViewController * flutterViewController = [[FlutterViewController alloc] init];
    [flutterViewController setInitialRoute:@"App"];
    
    flutterViewController.view.backgroundColor = [UIColor whiteColor];
    FlutterEventChannel *eventChannel = [FlutterEventChannel eventChannelWithName:@"App/Event/Channel" binaryMessenger:flutterViewController];
 
    [eventChannel setStreamHandler:self];

複製代碼

經過以上梳理咱們基本就能夠進行native反向主動給flutter發送數據

問題踩坑

native發送數據是NSDictionry不要進行內部嵌套：@{@"key":@{}}這樣是不經過的

channel命名建議

1. Android採用 packagename + eventType + channelname
2. iOS 採用 bundleidentifier + event type + channelname