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Flutter平台与iOS平台方法交互

Flutter平台与iOS平台方法交互

作者: z夜流星 | 来源:发表于2022-12-01 15:39 被阅读0次

一:我们先来看看flutter应用的启动流程

flutter应用的启动流程

在流程图里我们看到,应用启动先执行ios原生平台的main函数,之后才会执行flutter平台的main函数
ios应用启动后,会在ios原生平台的main()函数的代理方法里创建一个 FlutterViewController,并将 window的根页面设置为 FlutterViewController。这个FlutterViewController会隐式的创建一个FlutterEngine(flutter引擎)
flutter引擎实例对象一旦运行,就会执行 flutter中的main()函数

注意:在ios平台,我们写代码时要尽量保持FlutterEngine的复用,保证只有一个FlutterEngine对象,因为多个flutter引擎会导致fluttermain()方法执行多次;
而我们知道主函数main()都是在整个应用程序生命周期中只执行一次的,主函数执行多次会导致不可预知的逻辑错误。

二:flutter主动调用ios方法,ios方法被动响应。

1:首先:我们需要在ios应用启动的代理方法- (void)applicationDidFinishLaunching:(UIApplication *)application里注册对flutter平台的监听:
- (BOOL)application:(UIApplication *)application
    didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
  [GeneratedPluginRegistrant registerWithRegistry:self];
     
    //第一步:初始化ios调用flutter,用于ios平台主动调用flutter方法
    [[FlutterEvent sharedInstance] setUp];
     
    //第二步:初始化flutter调用ios,用于监听flutter传递过来的消息
    [[FlutterMethod sharedInstance] setUp];
     
  return [super application:application didFinishLaunchingWithOptions:launchOptions];
}
FlutterMethod.m 文件中, setUp()方法的实现
#import "FlutterMethod.h"
#import "FlutterMethodKey.h"
#import <Flutter/Flutter.h>
#import "AppDelegate.h"

// 通讯key
#define Key_deliver_methodChannel @"com.deliver.method"

/** 注册远程推送 */
 #define Key_RegisterRemotePush  @"register_remote_push";
/** 获取App信息 */ 
#define Key_GetAppInfo  @"get_appInfo";

@implementation FlutterMethod
 
static FlutterMethod* singleInstance = nil;
 
+ (instancetype)allocWithZone:(struct _NSZone *)zone {
     
    if(nil == singleInstance) {
        singleInstance = [super allocWithZone:zone];
    }
     
    return singleInstance;
}
 
+ (FlutterMethod *)sharedInstance {
     
    if(nil == singleInstance) {
        singleInstance = [[FlutterMethod alloc] init];
    }
     
    return singleInstance;
}
 
- (void)setUp {
    //直接获取根页面FlutterViewController;再获取到FlutterEngine。
    FlutterViewController* flutterVC = (FlutterViewController*) [UIApplication sharedApplication].delegate.window.rootViewController;
    id binarymessenger = flutterVC.engine.binaryMessenger;
    FlutterMethodChannel* methodChannel = [FlutterMethodChannel methodChannelWithName:Key_deliver_methodChannel binaryMessenger:binarymessenger];
    __weak typeof(self) weakSelf = self;
    [methodChannel setMethodCallHandler:^(FlutterMethodCall * _Nonnull call, FlutterResult  _Nonnull result) {
         
        NSLog(@"flutter传给ios的参数:%@",call.arguments);
         
        if([Key_RegisterRemotePush isEqualToString:call.method]) {
            //开始注册推送...
            [AppDelegate beginRegisterRemotePush];
            result(nil);
        }else if([Key_GetAppInfo isEqualToString:call.method]) {
            //获取应用信息
            NSString* appInfo = [weakSelf getAppInfo];
            result(appInfo);
        }
    }];
}
 
end
2:然后,在flutter平台需要调用ios原生方法时可以这样写:
void registerRemotePush() async {
 
  if(Platform.isIOS) {
    //注册推送功能,ios使用原生平台推送
    dynamic response = await FlutterMethodChannel.flutterCallNativeMethod(FlutterMethodKey.Key_RegisterRemotePush, {"data":"传点什么参数好呢???"});
    print("ios回传的参数:$response");
  }else if(Platform.isAndroid) {

  }
}
FlutterMethodChannel类的封装:
import 'dart:convert';
import 'package:flutter/services.dart';
 
/**
 * flutter 主动调用原生平台方法
 * */
 
class FlutterMethodKey {
 
  /// flutter调用(ios/android)方法,一个Key对应一个方法。
 
  static const Key_RegisterRemotePush = "register_remote_push";/** 注册远程推送 */
  static const Key_GetAppInfo  = "get_appInfo";/** 获取App信息 */
}
 
class FlutterMethodChannel {
 
  static const _Key_MethodChannel = "com.deliver.method";
  static const _platform = const MethodChannel(_Key_MethodChannel);
 
  // flutter调用原生
  static Future<dynamic> flutterCallNativeMethod(String methodKey, dynamic params) async {
 
    if(null==params){params = "";}
    print('flutter调用原生:$methodKey');
    print('flutter传给原生参数:$params');
 
    try {
      var result = await _platform.invokeMethod(methodKey,params);
      return result;
    }on PlatformException catch (e) {
      print("flutter调用原生平台方法出错:${e.message}");
      return e;
    }
  }
}

三: ios主动调用flutter方法,flutter被动响应

1:首先:我们需要在 flutter应用启动的 main.dart文件里注册对ios原生平台的监听:
void main() {
  runApp(MyApp());
}
 
class MyApp extends StatefulWidget {
  @override
  MyAppState createState() => MyAppState();
}
 
class MyAppState extends State<MyApp> {
 
  @override
  void initState() {
    super.initState();
    //注册原生调用flutter的监听
    FlutterEventChannel.registerEventChannel();
  }
}
FlutterEventChannel类的封装:
import 'dart:convert';
import 'package:flutter/services.dart';

/**
 * 原生平台方法调用 flutter 都会触发这里的回调。
 * */
 
class FlutterEventKey {
 
  ///(ios/android)调用flutter方法,一个Key对应一个方法。
 
  static const Key_ReceivePushToken = "receive_push_token";/** 获取到了推送token */
 
}
 
class FlutterEventChannel {
 
  static const _Key_EventChannel = "com.deliver.event";
  static const EventChannel _eventChannel = const EventChannel(_Key_EventChannel);
 
  ///注册(ios/android)调用flutter的事件回调
  static void registerEventChannel() {
     _eventChannel.receiveBroadcastStream().listen(
       _onNativeCallFlutterEvent,
       onError: _onNativeCallFlutterError,
     );
   }
 
   ///如果原生平台调用 flutter,下面的这个方法就会被触发执行。
   static void _onNativeCallFlutterEvent(dynamic event) {
    print("native平台给flutter传参数啦:$event");
    if(event is String) {
      var eventObject = json.decode(event);
      if(eventObject is Map) {
        var    data = eventObject["data"];
        String method = eventObject["method"];
 
        if(method == FlutterEventKey.Key_ReceivePushToken) {
          _savePushTokenToLocalDevice(data);
        }
      }
    }
 
   }
 
   ///如果调用 flutter 出错了,下面的这个方法就会执行。
   static void _onNativeCallFlutterError(Object error) {
 
   }
 
   //*****  10101010101010101010101010101010101010101010101010101010101010101010101010101010  *****//
 
  static void _savePushTokenToLocalDevice(String pushToken) {
    //将获取到的推送token保存到本地
   // save()...

  }
}
2:然后、在ios需要调用flutter的时候,我们可以这么写:
 #define  Key_ReceivePushToken @''receive_push_token" // 和flutter端 保持一致。
- (void)application:(UIApplication *)application didRegisterForRemoteNotificationsWithDeviceToken:(NSData *)deviceToken {
    //获取token
    NSString *token=@"获取token"
    NSLog(@"苹果apns推送获取token成功:%@",token);
    [[FlutterEvent sharedInstance] platformCallFlutter:Key_ReceivePushToken data:token];
}
FlutterEvent.m文件中, - (void)platformCallFlutter:(NSString*)methodKey data:(NSObject*)value方法的实现
#import "FlutterEvent.h"
#import <Flutter/Flutter.h>
#define Key_deliver_eventChannel @"com.deliver.event"
 
@interface FlutterEvent()<FlutterStreamHandler>
@property(nonatomic,strong)FlutterEventSink eventSink;;
@end
 
@implementation FlutterEvent
 
static FlutterEvent* singleInstance = nil;
 
+ (instancetype)allocWithZone:(struct _NSZone *)zone {
     
    if(nil == singleInstance) {
        singleInstance = [super allocWithZone:zone];
    }
     
    return singleInstance;
}
 
+ (FlutterEvent *)sharedInstance {
     
    if(nil == singleInstance) {
        singleInstance = [[FlutterEvent alloc] init];
    }
     
    return singleInstance;
}
 
- (void)setUp {
     
    FlutterViewController* flutterVC = (FlutterViewController*) [UIApplication sharedApplication].delegate.window.rootViewController;
    id binarymessenger = flutterVC.engine.binaryMessenger;
    FlutterEventChannel *eventChannel = [FlutterEventChannel eventChannelWithName:Key_deliver_eventChannel binaryMessenger:(NSObject<FlutterBinaryMessenger> *)binarymessenger];
    [eventChannel setStreamHandler:self];
}
 
- (void)platformCallFlutter:(NSString *)methodKey data:(NSObject *)value {
     
    if(nil == methodKey) {
        return;
    }
     
    NSDictionary* dataDic = @{@"method":methodKey,@"data":value};
    NSData* data = [NSJSONSerialization dataWithJSONObject:dataDic options:NSJSONWritingPrettyPrinted error:nil];
    NSString* jsonStr = [[NSString alloc] initWithData:data encoding:NSUTF8StringEncoding];
     
    if(self.eventSink) {
        self.eventSink(jsonStr);
    }
}
 
#pragma mark - FlutterStreamHandler
- (FlutterError *)onListenWithArguments:(id)arguments eventSink:(FlutterEventSink)events {
    self.eventSink = events;
    return nil;
}
 
- (FlutterError *)onCancelWithArguments:(id)arguments {
    NSLog(@"flutter给ios的参数(arguments):%@",arguments);
    return nil;
}
 
@end

四:总结

1:flutter调用ios,使用 MethodChannel类的 invokeMethod()
2:ios调用flutter,使用 EventChannel 类的 receiveBroadcastStream()
flutter与iOS通讯流程

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