如何使用React Native正確地從橋接的iOS模塊發出和接收事件到JavaScript？

Question

我有一個React Native應用程序，並希望從Obj-C發送一個事件來測試應用程序事件/發射系統的工作方式。 我已經閱讀了所有文檔，翻閱了本地回購的示例以了解示例，但仍然不知道我的代碼有什么問題。

我知道我的Obj-C會觸發，因為我已經逐步完成了Xcode中的代碼，並且self.bridge.eventDispatcher不是nil 。 我還知道，通過控制台日志，模擬器中呈現的主要React Native組件會安裝並呈現。 問題是我沒有看到任何這些通知的控制台輸出。 我可能錯誤地要求這個ApplicationManager類，或者訂閱錯誤的“東西”來監聽事件。 我可能做錯很多/很差的事情:-)

這是我的Obj-C導出模塊：

@implementation ApplicationManager

RCT_EXPORT_MODULE();

@synthesize bridge = _bridge;

- (instancetype)init {
  self = [super init];
  if ( self ) {
    NSNotificationCenter * notificationCenter = [NSNotificationCenter defaultCenter];
    [notificationCenter addObserver:self selector:@selector(applicationDidEnterBackground:) name:UIApplicationDidEnterBackgroundNotification object:nil];
    [notificationCenter addObserver:self selector:@selector(applicationWillEnterForeground:) name:UIApplicationWillEnterForegroundNotification object:nil];
    [notificationCenter addObserver:self selector:@selector(applicationDidFinishLaunching:) name:UIApplicationDidFinishLaunchingNotification object:nil];
    [notificationCenter addObserver:self selector:@selector(applicationDidBecomeActive:) name:UIApplicationDidBecomeActiveNotification object:nil];
    [notificationCenter addObserver:self selector:@selector(applicationWillResignActive:) name:UIApplicationWillResignActiveNotification object:nil];
    [notificationCenter addObserver:self selector:@selector(applicationDidReceiveMemoryWarning:) name:UIApplicationDidReceiveMemoryWarningNotification object:nil];
  }

  return self;
}

- (void)dealloc {
  [[NSNotificationCenter defaultCenter] removeObserver:self];
}

- (void)applicationDidEnterBackground:(NSNotification *)notification {
  [self dispatchAppEventWithName:@"ApplicationDidEnterBackground" body:nil];
}

- (void)applicationWillEnterForeground:(NSNotification *)notification {
  [self dispatchAppEventWithName:@"ApplicationWillEnterBackground" body:nil];
}

- (void)applicationDidFinishLaunching:(NSNotification *)notification {
  [self dispatchAppEventWithName:@"ApplicationDidFinishLaunching" body:nil];
}

- (void)applicationDidBecomeActive:(NSNotification *)notification {
  [self dispatchAppEventWithName:@"ApplicationDidBecomeActive" body:nil];
}

- (void)applicationWillResignActive:(NSNotification *)notification {
  [self dispatchAppEventWithName:@"ApplicationWillResignActive" body:nil];
}

- (void)applicationDidReceiveMemoryWarning:(NSNotification *)notification {
  [self dispatchAppEventWithName:@"ApplicationDidReceiveMemoryWarning" body:nil];
}

- (void)dispatchAppEventWithName:(NSString *)name body:(NSDictionary *)body {
  [self.bridge.eventDispatcher sendAppEventWithName:name body:body];
}

@end

我知道這些事件和通知已經在RCTAppState可用，但我正在嘗試自己推出一個解決方案來學習：

https://github.com/facebook/react-native/blob/2f6e7336cb96bf14d47554ae0db1836075ea809e/React/Modules/RCTAppState.m

我嘗試過使用兩者：

[self.bridge.eventDispatcher sendAppEventWithName:name body:body];

和：

[self.bridge.eventDispatcher sendDeviceEventWithName:name body:body];

沒有任何成功。 除了用於JavaScript端調度事件的接收者類之外，我不確定這兩種方法之間的區別。

這是相關的React Native代碼：

var {
  AppRegistry,
  StyleSheet,
  Text,
  View,
  TabBarIOS,
  NativeAppEventEmitter,
} = React;

// ... other code omitted for brevity ... 

componentDidMount: function() {
    console.log("main component didMount");
    debugger;
    NativeAppEventEmitter.addListener("ApplicationDidFinishLaunching", (reminder) => { console.log("app event emitter: ApplicationDidFinishLaunching:", reminder)} );
 },

調試器行在Chrome調試器中命中， NativeAppEventEmitter undefined ，而是：

NativeAppEventEmitter
EventEmitter {_subscriber: EventSubscriptionVendor}_subscriber:
EventSubscriptionVendor__proto__: EventEmitter

我的猜測是我做錯了什么，但我不知道是什么。 任何幫助將不勝感激。

Answer 1

訂閱事件的代碼和發送事件的代碼很好。

您遇到的問題是因為ApplicationDidFinishLaunching事件在您訂閱事件的componentDidMount之前觸發。