如何在混编Objective-C与Swift的Flutter项目中实现EventChannel？

针对你在混编项目中需要将Objective-C类里的NFC/BLE回调通过Flutter EventChannel传递给Flutter页面的需求，以下是具体实现步骤：

1. 修正Objective-C类的Block属性与方法 #

首先调整MyController.h中的Block属性声明，将strong改为copy（Block属性规范用法，避免栈Block释放问题），并补充设置Block的方法声明：

typedef void(^NfcBlock)(bool isSuccess);
typedef void(^BleBlock)(bool isSuccess);

@interface MyController : NSObject<NfcDelegate, BleServiceDelegate,CBCentralManagerDelegate>

@property (nonatomic,strong) BlePassService *blePassService;
@property (nonatomic,strong) NfcPassService *nfcService;
@property (nonatomic,strong) MobilePass *mobilePass;
@property (nonatomic, copy) NfcBlock nfcBlock; // 改为copy
@property (nonatomic, copy) BleBlock bleBlock; // 改为copy

// 补充设置Block的方法声明
- (void)setNfcBlock:(NfcBlock)nfcBlock;
- (void)setBleBlock:(BleBlock)bleBlock;

@end

在MyController.m中实现设置方法，并在NFC/BLE代理回调里触发Block：

@implementation MyController

- (void)setNfcBlock:(NfcBlock)nfcBlock {
    _nfcBlock = nfcBlock;
}

- (void)setBleBlock:(BleBlock)bleBlock {
    _bleBlock = bleBlock;
}

// NFC代理方法示例（根据你的实际代理方法调整）
- (void)nfcOperationDidFinishWithSuccess:(BOOL)isSuccess {
    if (self.nfcBlock) {
        self.nfcBlock(isSuccess);
    }
}

// BLE代理方法示例（根据你的实际代理方法调整）
- (void)bleConnectionDidFinishWithSuccess:(BOOL)isSuccess {
    if (self.bleBlock) {
        self.bleBlock(isSuccess);
    }
}

@end

2. 在Swift的AppDelegate中配置Flutter EventChannel #

首先添加EventChannel相关属性与协议实现，将Block回调与EventChannel的事件发送关联：

import UIKit
import Flutter

@UIApplicationMain
class AppDelegate: FlutterAppDelegate {
    private var eventSink: FlutterEventSink?
    private var passKit: MyController? // 你的MyController实例

    override func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
        GeneratedPluginRegistrant.register(with: self)
        
        // 初始化EventChannel
        guard let controller = window?.rootViewController as? FlutterViewController else {
            return super.application(application, didFinishLaunchingWithOptions: launchOptions)
        }
        let eventChannel = FlutterEventChannel(name: "com.your.app/nfc_ble_events", binaryMessenger: controller.binaryMessenger)
        eventChannel.setStreamHandler(self)
        
        // 初始化passKit（根据你的实际逻辑调整）
        passKit = MyController()
        
        return super.application(application, didFinishLaunchingWithOptions: launchOptions)
    }

    // NFC回调方法，通过EventChannel发送事件到Flutter
    func nfcCallback(isSuccess: Bool) {
        eventSink?(["type": "nfc", "success": isSuccess])
    }

    // BLE回调方法，通过EventChannel发送事件到Flutter
    func bleCallback(isSuccess: Bool) {
        eventSink?(["type": "ble", "success": isSuccess])
    }

    // 原有的方法（保持你的业务逻辑）
    func handleMethodCall(_ call: FlutterMethodCall, result: @escaping FlutterResult) {
        switch call.method {
        case "initState":
            guard let passKit = passKit else { return }
            passKit.initial()
            passKit.setNfcBlock(nfcCallback)
            passKit.setBleBlock(bleCallback)
            result("success")
        // 其他方法处理...
        default:
            result(FlutterMethodNotImplemented)
        }
    }
}

// 实现FlutterStreamHandler协议
extension AppDelegate: FlutterStreamHandler {
    func onListen(withArguments arguments: Any?, eventSink events: @escaping FlutterEventSink) -> FlutterError? {
        eventSink = events
        return nil
    }
    
    func onCancel(withArguments arguments: Any?) -> FlutterError? {
        eventSink = nil
        return nil
    }
}

3. Flutter端监听EventChannel #

在Flutter页面中监听事件，处理来自原生的NFC/BLE结果：

import 'package:flutter/services.dart';

class YourFlutterPage extends StatefulWidget {
  const YourFlutterPage({super.key});

  @override
  State<YourFlutterPage> createState() => _YourFlutterPageState();
}

class _YourFlutterPageState extends State<YourFlutterPage> {
  static const EventChannel _eventChannel = EventChannel('com.your.app/nfc_ble_events');

  @override
  void initState() {
    super.initState();
    // 监听原生事件
    _eventChannel.receiveBroadcastStream().listen((event) {
      String type = event['type'];
      bool success = event['success'];
      if (type == 'nfc') {
        // 处理NFC操作结果
        print("NFC操作结果：$success");
      } else if (type == 'ble') {
        // 处理BLE连接结果
        print("BLE连接结果：$success");
      }
    });
  }

  @override
  Widget build(BuildContext context) {
    // 你的页面UI
    return Scaffold(
      appBar: AppBar(title: const Text("NFC/BLE测试")),
    );
  }
}

关键注意点 #

• 确保Objective-C中的代理方法正确触发Block，比如在NFC/BLE操作完成的回调里调用self.nfcBlock(isSuccess)；
• EventChannel的名称要保持原生与Flutter端一致（示例中为com.your.app/nfc_ble_events）；
• 当不需要监听时，eventSink要置为nil，避免内存泄漏。

内容的提问来源于stack exchange，提问作者bakboem