最后，

Question

我创建了以下类（精简版），这是对完整文件的引用 https://github.com/cotyembry/CastRemoteNative/blob/7e74dbc56f037cc61241f6ece24a94d8c52abb32/root/ios/CastRemoteNative/NativeMethods.swift

@objc(NativeMethods)
class NativeMethods: RCTEventEmitter {
  @objc(sendEventToJSFromJS)
  func sendEventToJSFromJS {
    self.emitEvent(eventName: "test", body: "bodyTestString")
  }
  func emitEvent(eventName: String: body: Any) {
    self.sendEvent(withName: eventName, body: body)
  }
}

这非常有效，当我调用emitEvent方法时，我的javascript代码中会调用我的回调侦听器，如下所示，它是一个改进的代码片段来自 https://github.com/cotyembry/CastRemoteNative/blob/7e74dbc56f037cc61241f6ece24a94d8c52abb32/root/js/Components/ChromecastDevicesModal.js

从javascript端

import {
  NativeModules,
  NativeEventEmitter
} from 'react-native'

//here I bring in the swift class to use inside javascript
var NativeMethods = NativeModules.NativeMethods;

//create an event emitter to use to listen for the native events when they occur
this.eventEmitter = new NativeEventEmitter(NativeMethods);
//listen for the event once it sends
this.subscription = this.eventEmitter.addListener('test', (body) => { console.log('in test event listener callback', body)});

NativeMethods.sendEventToJSFromJS() //call the native method written in swift

我只是在javascript按下按钮时调用了sendEventToJSFromJS方法

同样，这有效，console.log('in test event listener callback', body)代码可以在javascript端运行并运行

我的问题，这不起作用：

如果我在定义类后在swift文件中执行以下操作，则无效：

var nativeMethodsInstance = nativeMethods()
nativeMethodsInstance.sendEventToJSFromSwift()

为什么呢？因为抛出以下错误：

Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'bridge is not set. This is probably because you've explicitly synthesized the bridge in NativeMethods, even though it's inherited from RCTEventEmitter.'

那么，在创建instance NativeMethods时，与之相比......有什么区别？

有关其他信息：

当我在.h和.m文件而不是.swift文件中编写这些相同的代码片段时，Objective-C获得了相同的桥接未设置问题

我找到了在本机代码中打印错误消息的位置，但它只有变量

_bridge

正在检查是否是nil

这个错误的文件来自：

RCTEventEmitter.h
RCTEventEmitter.c

这里是RCTEventEmitter.c的完整片段

- (void)sendEventWithName:(NSString *)eventName body:(id)body
{


  RCTAssert(_bridge != nil, @"bridge is not set. This is probably because you've "
        "explicitly synthesized the bridge in %@, even though it's inherited "
        "from RCTEventEmitter.", [self class]);

  if (RCT_DEBUG && ![[self supportedEvents] containsObject:eventName]) {
    RCTLogError(@"`%@` is not a supported event type for %@. Supported events are: `%@`",
                eventName, [self class], [[self supportedEvents] componentsJoinedByString:@"`, `"]);
  }
  if (_listenerCount > 0) {
    [_bridge enqueueJSCall:@"RCTDeviceEventEmitter"
                    method:@"emit"
                      args:body ? @[eventName, body] : @[eventName]
                completion:NULL];
  } else {
    RCTLogWarn(@"Sending `%@` with no listeners registered.", eventName);
  }
}

这个_bridge值在哪里被设置以及它是如何设置的，所以我知道，在它失败的情况下如何设置它

我在RCTEventEmitter.h中也发现了以下内容

@property (nonatomic, weak) RCTBridge *bridge;

在给出的错误中，它提到桥接器是在RCTEventEmitter中继承的，所以这可能是weak属性bridge部分的问题吗？

或者我是否需要改变策略，以便我一起完成这项工作？

我知道这可能与我没有完全理解

有关

@synthesize bridge = _bridge;

部分代码和混合的所有语言都没有多大帮助......

这真的很难，所以任何帮助都会非常感激！非常感谢你的时间

这是项目历史代码代表上述问题代码的完整项目的链接（因为我已经对项目进行了更改）：

https://github.com/cotyembry/CastRemoteNative/tree/7e74dbc56f037cc61241f6ece24a94d8c52abb32

Answer 1

我想通了

警告：此解决方案使用弃用方法反应原生方法 - 我无法弄清楚如何“正确”继承RCTEventEmitter并发送事件......每次我尝试_bridge最终会成为nil

确保Swift桥接到Objective C（如果你使用swift将事件发送到javascript）

不创建导出的Native模块的实例（无论是用Swift还是Objective C编写）

让React Native的底层实现执行此操作，并为每个需要发送事件的类，将特定的Native Class Objective C Implementation代码或Swift代码（Native Module）导出到React-Native。这允许javascript能够收听事件

var publicBridgeHelperInstance = PublicBridgeHelper()  //instantiate the  the objective c class from inside the .swift file to use later when needing to get a reference to the bridge to send an event to javascript written in react native

@objc(DeviceManager)             //export swift module to objective c
class DeviceManager: NSObject {

  @objc(deviceDidComeOnline:)    //expose the function to objective c
  public func deviceDidComeOnline(_ device: GCKDevice) {
    //imagine this deviceDidComeOnline function gets called from something from the Native code (totally independent of javascript) - honestly this could be called from a native button click as well just to test it works...

    //emit an event to a javascript function that is a in react native Component listening for the event like so:

    //1. get a reference to the bridge to send an event through from Native to Javascript in React Native (here is where my custom code comes in to get this to actually work)
    let rnBridge = publicBridgeHelperInstance.getBridge()  //this gets the bridge that is stored in the AppDelegate.m file that was set from the `rootView.bridge` variable (more on this later)

    //(if you want to print the bridge here to make sure it is not `nil` go ahead:
    print("rnBridge = \(rnBridge)")

    //2. actually send the event through the eventDispatcher
    rnBridge?.eventDispatcher().sendAppEvent(withName: "test", body: "testBody data!!!")
  }
}

在AppDelegate.h put中（除了文件中已有的代码）

#import "YourProjectsBridgingHeaderToMakeThisCodeAvailableInSwift.h"  //replace this with your actual header you created when creating a swift file (google it if you dont know how to bridge swift to objective c)

@interface PublicBridgeHelper: NSObject
  -(RCTBridge*)getBridge;
@end

在AppDelegate.m put中（除了文件中已有的代码）

#import <React/RCTRootView.h>

RCTBridge *rnBridgeFromRootView;

@implementation PublicBridgeHelper    //this is created to SIMPLY return rnBridgeFromRootView defined above over to my Swift class when actually sending the event to javascript that defines a react native Component
-(RCTBridge*)getBridge {
  NSLog(@"rnBridgeFromRootView = @%@", rnBridgeFromRootView);
  return rnBridgeFromRootView;
}

重要 - 还要确保将以下代码行添加到Objective C .h的桥接标头中，以使此PublicBridgeHelper定义可用于.swift代码

#import "AppDelegate.h"

最后，

现在向您展示如何设置AppDelegate.m中使用的rnBridgeFromRootView变量（在将事件发送到javascript之前返回并在.swift代码中使用）

打开AppDelegate.m并在

的方法正文中

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions { ... }

在实例化rootView变量

的代码行之后包含以下内容

即。在可能看起来像

的行之后

RCTRootView *rootView = [[RCTRootView alloc] initWithBundleURL:jsCodeLocation moduleName:@"YourProjecNameProbably" initialProperties:nil launchOptions:launchOptions];

添加：

rnBridgeFromRootView = rootView.bridge  //set the bridge to  be exposed and returned later and used by the swift class

现在解释.swift文件中的publicBridgeHelperInstance.getBridge()部分

publicBridgeHelper是一个目标c类的实例，它允许swift类能够获得对native本机桥的引用

如果您在阅读本文后仍然无法理解我的回答，我会在其上制作视频，您可以在此处观看：

https://www.youtube.com/watch?v=GZj-Vm9cQIg&t=9s

从swift或objective-c

1 个答案:

最后，