Updated AppState module to use new emitter system

Summary: AppState now subclasses NativeEventEmitter instead of using global RCTDeviceEventEmitter.

Reviewed By: javache

Differential Revision: D3310488

fbshipit-source-id: f0116599223f4411307385c0dab683659d8d63b6

Examples/UIExplorer/UIExplorerIntegrationTests/RCTRootViewIntegrationTests.m

@@ -66,9 +66,13 @@ typedef void (^ControlBlock)(RCTRootView*);
 
 - (void)rootViewDidChangeIntrinsicSize:(RCTRootView *)rootView
 {
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wdeprecated-declarations"
+
   [rootView.bridge.eventDispatcher sendAppEventWithName:@"rootViewDidChangeIntrinsicSize"
                                                    body:@{@"width": @(rootView.intrinsicSize.width),
                                                           @"height": @(rootView.intrinsicSize.height)}];
+#pragma clang diagnostic pop
 }
 
 @end

Examples/UIExplorer/UIExplorerUnitTests/RCTEventDispatcherTests.m

@@ -103,8 +103,13 @@
   [[_bridge expect] enqueueJSCall:_JSMethod
                              args:[_testEvent arguments]];
 
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wdeprecated-declarations"
+
   [_eventDispatcher sendDeviceEventWithName:_eventName body:_body];
 
+#pragma clang diagnostic pop
+
   [_bridge verify];
 }
 

Examples/UIExplorer/UIExplorerUnitTests/RCTModuleInitNotificationRaceTests.m

@@ -41,11 +41,16 @@
 
 RCT_EXPORT_MODULE()
 
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wdeprecated-implementations"
+
 - (NSArray<NSString *> *)customDirectEventTypes
 {
   return @[@"foo"];
 }
 
+#pragma clang diagnostic pop
+
 @end
 
 

Libraries/AppState/AppState.js

@@ -11,18 +11,12 @@
  */
 'use strict';
 
-var Map = require('Map');
+const NativeEventEmitter = require('NativeEventEmitter');
-var NativeModules = require('NativeModules');
+const NativeModules = require('NativeModules');
-var RCTDeviceEventEmitter = require('RCTDeviceEventEmitter');
+const RCTAppState = NativeModules.AppState;
-var RCTAppState = NativeModules.AppState;
 
-var logError = require('logError');
+const logError = require('logError');
-var invariant = require('fbjs/lib/invariant');
+const invariant = require('fbjs/lib/invariant');
-
-var _eventHandlers = {
-  change: new Map(),
-  memoryWarning: new Map(),
-};
 
 /**
  * `AppState` can tell you if the app is in the foreground or background,
@@ -36,8 +30,9 @@ var _eventHandlers = {
  *  - `active` - The app is running in the foreground
  *  - `background` - The app is running in the background. The user is either
  *     in another app or on the home screen
- *  - `inactive` - This is a transition state that currently never happens for
+ *  - `inactive` - This is a state that occurs when transitioning between
- *     typical React Native apps.
+ *  	 foreground & background, and during periods of inactivity such as
+ *  	 entering the Multitasking view or in the event of an incoming call
  *
  * For more information, see
  * [Apple's documentation](https://developer.apple.com/library/ios/documentation/iPhone/Conceptual/iPhoneOSProgrammingGuide/TheAppLifeCycle/TheAppLifeCycle.html)
@@ -75,13 +70,58 @@ var _eventHandlers = {
  * state will happen only momentarily.
  */
 
-var AppState = {
+class AppState extends NativeEventEmitter {
 
-  /**
+  _eventHandlers: Object;
+  currentState: ?string;
+
+  constructor() {
+    super(RCTAppState);
+
+    this._eventHandlers = {
+      change: new Map(),
+      memoryWarning: new Map(),
+    };
+
+    // TODO: getCurrentAppState callback seems to be called at a really late stage
+    // after app launch. Trying to get currentState when mounting App component
+    // will likely to have the initial value here.
+    // Initialize to 'active' instead of null.
+    this.currentState = 'active';
+    
+    // TODO: this is a terrible solution - in order to ensure `currentState` prop
+    // is up to date, we have to register an observer that updates it whenever
+    // the state changes, even if nobody cares. We should just deprecate the
+    // `currentState` property and get rid of this.
+    this.addListener(
+      'appStateDidChange',
+      (appStateData) => {
+        this.currentState = appStateData.app_state;
+      }
+    );
+    
+    // TODO: see above - this request just populates the value of `currentState`
+    // when the module is first initialized. Would be better to get rid of the prop
+    // and expose `getCurrentAppState` method directly.
+    RCTAppState.getCurrentAppState(
+      (appStateData) => {
+        this.currentState = appStateData.app_state;
+      },
+      logError
+    );
+  }
+
+  /**   
    * Add a handler to AppState changes by listening to the `change` event type
    * and providing the handler
+   *
+   * TODO: now that AppState is a subclass of NativeEventEmitter, we could deprecate
+   * `addEventListener` and `removeEventListener` and just use `addListener` and
+   * `listener.remove()` directly. That will be a breaking change though, as both
+   * the method and event names are different (addListener events are currently
+   * required to be globally unique).
    */
-  addEventListener: function(
+  addEventListener(
     type: string,
     handler: Function
   ) {
@@ -90,24 +130,24 @@ var AppState = {
       'Trying to subscribe to unknown event: "%s"', type
     );
     if (type === 'change') {
-      _eventHandlers[type].set(handler, RCTDeviceEventEmitter.addListener(
+      this._eventHandlers[type].set(handler, this.addListener(
         'appStateDidChange',
         (appStateData) => {
           handler(appStateData.app_state);
         }
       ));
     } else if (type === 'memoryWarning') {
-      _eventHandlers[type].set(handler, RCTDeviceEventEmitter.addListener(
+      this._eventHandlers[type].set(handler, this.addListener(
         'memoryWarning',
         handler
       ));
     }
-  },
+  }
 
   /**
    * Remove a handler by passing the `change` event type and the handler
    */
-  removeEventListener: function(
+  removeEventListener(
     type: string,
     handler: Function
   ) {
@@ -115,28 +155,14 @@ var AppState = {
       ['change', 'memoryWarning'].indexOf(type) !== -1,
       'Trying to remove listener for unknown event: "%s"', type
     );
-    if (!_eventHandlers[type].has(handler)) {
+    if (!this._eventHandlers[type].has(handler)) {
       return;
     }
-    _eventHandlers[type].get(handler).remove();
+    this._eventHandlers[type].get(handler).remove();
-    _eventHandlers[type].delete(handler);
+    this._eventHandlers[type].delete(handler);
-  },
+  }
-
-  currentState: ('active' : ?string),
 };
 
-RCTDeviceEventEmitter.addListener(
+AppState = new AppState();
-  'appStateDidChange',
-  (appStateData) => {
-    AppState.currentState = appStateData.app_state;
-  }
-);
-
-RCTAppState.getCurrentAppState(
-  (appStateData) => {
-    AppState.currentState = appStateData.app_state;
-  },
-  logError
-);
 
 module.exports = AppState;

Libraries/AppState/AppStateIOS.js

@@ -11,20 +11,8 @@
  */
 'use strict';
 
-var warning = require('fbjs/lib/warning');
+const AppState = require('AppState');
 
-class AppStateIOS {
+console.warn('AppStateIOS is deprecated. Use AppState instead');
 
-  static addEventListener(type, handler) {
+module.exports = AppState;
-    warning(false, 'Cannot listen to AppStateIOS events on Android.');
-  }
-
-  static removeEventListener(type, handler) {
-    warning(false, 'Cannot remove AppStateIOS listener on Android.');
-  }
-
-}
-
-AppStateIOS.currentState = null;
-
-module.exports = AppStateIOS;

Libraries/AppStateIOS/AppStateIOS.ios.js

@@ -1,147 +0,0 @@
-/**
- * Copyright (c) 2015-present, Facebook, Inc.
- * All rights reserved.
- *
- * This source code is licensed under the BSD-style license found in the
- * LICENSE file in the root directory of this source tree. An additional grant
- * of patent rights can be found in the PATENTS file in the same directory.
- *
- * @providesModule AppStateIOS
- * @flow
- */
-'use strict';
-
-var NativeModules = require('NativeModules');
-var RCTDeviceEventEmitter = require('RCTDeviceEventEmitter');
-var RCTAppState = NativeModules.AppState;
-
-var logError = require('logError');
-var invariant = require('fbjs/lib/invariant');
-
-var _eventHandlers = {
-  change: new Map(),
-  memoryWarning: new Map(),
-};
-
-/**
- * `AppStateIOS` can tell you if the app is in the foreground or background,
- * and notify you when the state changes.
- *
- * AppStateIOS is frequently used to determine the intent and proper behavior when
- * handling push notifications.
- *
- * ### iOS App States
- *
- *  - `active` - The app is running in the foreground
- *  - `background` - The app is running in the background. The user is either
- *     in another app or on the home screen
- *  - `inactive` - This is a state that occurs when transitioning between
- *  	 foreground & background, and during periods of inactivity such as
- *  	 entering the Multitasking view or in the event of an incoming call
- *
- * For more information, see
- * [Apple's documentation](https://developer.apple.com/library/ios/documentation/iPhone/Conceptual/iPhoneOSProgrammingGuide/TheAppLifeCycle/TheAppLifeCycle.html)
- *
- * ### Basic Usage
- *
- * To see the current state, you can check `AppStateIOS.currentState`, which
- * will be kept up-to-date. However, `currentState` will be null at launch
- * while `AppStateIOS` retrieves it over the bridge.
- *
- * ```
- * getInitialState: function() {
- *   return {
- *     currentAppState: AppStateIOS.currentState,
- *   };
- * },
- * componentDidMount: function() {
- *   AppStateIOS.addEventListener('change', this._handleAppStateChange);
- * },
- * componentWillUnmount: function() {
- *   AppStateIOS.removeEventListener('change', this._handleAppStateChange);
- * },
- * _handleAppStateChange: function(currentAppState) {
- *   this.setState({ currentAppState, });
- * },
- * render: function() {
- *   return (
- *     <Text>Current state is: {this.state.currentAppState}</Text>
- *   );
- * },
- * ```
- *
- * This example will only ever appear to say "Current state is: active" because
- * the app is only visible to the user when in the `active` state, and the null
- * state will happen only momentarily.
- */
-
-var AppStateIOS = {
-
-  /**
-   * Add a handler to AppState changes by listening to the `change` event type
-   * and providing the handler
-   */
-  addEventListener: function(
-    type: string,
-    handler: Function
-  ) {
-    invariant(
-      ['change', 'memoryWarning'].indexOf(type) !== -1,
-      'Trying to subscribe to unknown event: "%s"', type
-    );
-    if (type === 'change') {
-      _eventHandlers[type].set(handler, RCTDeviceEventEmitter.addListener(
-        'appStateDidChange',
-        (appStateData) => {
-          handler(appStateData.app_state);
-        }
-      ));
-    } else if (type === 'memoryWarning') {
-      _eventHandlers[type].set(handler, RCTDeviceEventEmitter.addListener(
-        'memoryWarning',
-        handler
-      ));
-    }
-  },
-
-  /**
-   * Remove a handler by passing the `change` event type and the handler
-   */
-  removeEventListener: function(
-    type: string,
-    handler: Function
-  ) {
-    invariant(
-      ['change', 'memoryWarning'].indexOf(type) !== -1,
-      'Trying to remove listener for unknown event: "%s"', type
-    );
-    if (!_eventHandlers[type].has(handler)) {
-      return;
-    }
-    _eventHandlers[type].get(handler).remove();
-    _eventHandlers[type].delete(handler);
-  },
-
-  // TODO: getCurrentAppState callback seems to be called at a really late stage
-  // after app launch. Trying to get currentState when mounting App component
-  // will likely to have the initial value here.
-  // Initialize to 'active' instead of null.
-  currentState: ('active' : ?string),
-
-};
-
-RCTDeviceEventEmitter.addListener(
-  'appStateDidChange',
-  (appStateData) => {
-    AppStateIOS.currentState = appStateData.app_state;
-  }
-);
-
-RCTAppState.getCurrentAppState(
-  (appStateData) => {
-    AppStateIOS.currentState = appStateData.app_state;
-  },
-  logError
-);
-
-module.exports = AppStateIOS;

Libraries/EventEmitter/RCTDeviceEventEmitter.js

@@ -30,31 +30,35 @@ class RCTDeviceEventEmitter extends EventEmitter {
     super(sharedSubscriber);
     this.sharedSubscriber = sharedSubscriber;
   }
+  
+  _nativeEventModule(eventType: ?string) {
+    if (eventType) {
+      if (eventType.lastIndexOf('statusBar', 0) === 0) {
+        console.warn('`%s` event should be registered via the StatusBarIOS module', eventType);
+        return require('StatusBarIOS');
+      }
+      if (eventType.lastIndexOf('keyboard', 0) === 0) {
+        console.warn('`%s` event should be registered via the Keyboard module', eventType);
+        return require('Keyboard');
+      }
+      if (eventType === 'appStateDidChange' || eventType === 'memoryWarning') {
+        console.warn('`%s` event should be registered via the AppState module', eventType);
+        return require('AppState');
+      }
+    }
+    return null;
+  }
 
   addListener(eventType: string, listener: Function, context: ?Object): EmitterSubscription {
-    if (eventType.lastIndexOf('statusBar', 0) === 0) {
+    const eventModule = this._nativeEventModule(eventType);
-      console.warn('`%s` event should be registered via the StatusBarIOS module', eventType);
+    return eventModule ? eventModule.addListener(eventType, listener, context)
-      return require('StatusBarIOS').addListener(eventType, listener, context);
+                       : super.addListener(eventType, listener, context);
-    }
-    if (eventType.lastIndexOf('keyboard', 0) === 0) {
-      console.warn('`%s` event should be registered via the Keyboard module', eventType);
-      return require('Keyboard').addListener(eventType, listener, context);
-    }
-    return super.addListener(eventType, listener, context);
   }
 
   removeAllListeners(eventType: ?string) {
-    if (eventType) {
+    const eventModule = this._nativeEventModule(eventType);
-      if (eventType.lastIndexOf('statusBar', 0) === 0) {
+    (eventModule && eventType) ? eventModule.removeAllListeners(eventType)
-        console.warn('statusBar events should be unregistered via the StatusBarIOS module');
+                               : super.removeAllListeners(eventType);
-        return require('StatusBarIOS').removeAllListeners(eventType);
-      }
-      if (eventType.lastIndexOf('keyboard', 0) === 0) {
-        console.warn('keyboard events should be unregistered via the Keyboard module');
-        return require('Keyboard').removeAllListeners(eventType);
-      }
-    }
-    super.removeAllListeners(eventType);
   }
 
   removeSubscription(subscription: EmitterSubscription) {

Libraries/Geolocation/RCTLocationObserver.m

@@ -279,8 +279,11 @@ RCT_EXPORT_METHOD(getCurrentPosition:(RCTLocationOptions)options
 
   // Send event
   if (_observingLocation) {
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wdeprecated-declarations"
     [_bridge.eventDispatcher sendDeviceEventWithName:@"geolocationDidChange"
                                                 body:_lastLocationEvent];
+#pragma clang diagnostic pop
   }
 
   // Fire all queued callbacks
@@ -321,8 +324,11 @@ RCT_EXPORT_METHOD(getCurrentPosition:(RCTLocationOptions)options
 
   // Send event
   if (_observingLocation) {
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wdeprecated-declarations"
     [_bridge.eventDispatcher sendDeviceEventWithName:@"geolocationError"
                                                 body:jsError];
+#pragma clang diagnostic pop
   }
 
   // Fire all queued error callbacks

Libraries/Network/RCTNetInfo.m

@@ -51,8 +51,11 @@ static void RCTReachabilityCallback(__unused SCNetworkReachabilityRef target, SC
 
   if (![status isEqualToString:self->_status]) {
     self->_status = status;
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wdeprecated-declarations"
     [self->_bridge.eventDispatcher sendDeviceEventWithName:@"networkStatusDidChange"
                                                       body:@{@"network_info": status}];
+#pragma clang diagnostic pop
   }
 }
 

Libraries/Network/RCTNetworking.m

@@ -346,8 +346,11 @@ RCT_EXPORT_MODULE()
   }
 
   NSArray<id> *responseJSON = @[task.requestID, responseText ?: @""];
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wdeprecated-declarations"
   [_bridge.eventDispatcher sendDeviceEventWithName:@"didReceiveNetworkData"
                                               body:responseJSON];
+#pragma clang diagnostic pop
 }
 
 - (void)sendRequest:(NSURLRequest *)request
@@ -361,7 +364,10 @@ RCT_EXPORT_MODULE()
   RCTURLRequestProgressBlock uploadProgressBlock = ^(int64_t progress, int64_t total) {
     dispatch_async(_methodQueue, ^{
       NSArray *responseJSON = @[task.requestID, @((double)progress), @((double)total)];
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wdeprecated-declarations"
       [_bridge.eventDispatcher sendDeviceEventWithName:@"didSendNetworkData" body:responseJSON];
+#pragma clang diagnostic pop
     });
   };
 
@@ -379,8 +385,11 @@ RCT_EXPORT_MODULE()
       }
       id responseURL = response.URL ? response.URL.absoluteString : [NSNull null];
       NSArray<id> *responseJSON = @[task.requestID, @(status), headers, responseURL];
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wdeprecated-declarations"
       [_bridge.eventDispatcher sendDeviceEventWithName:@"didReceiveNetworkResponse"
                                                   body:responseJSON];
+#pragma clang diagnostic pop
     });
   };
 
@@ -401,8 +410,11 @@ RCT_EXPORT_MODULE()
                                 error.code == kCFURLErrorTimedOut ? @YES : @NO
                                 ];
 
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wdeprecated-declarations"
       [_bridge.eventDispatcher sendDeviceEventWithName:@"didCompleteNetworkResponse"
                                                   body:responseJSON];
+#pragma clang diagnostic pop
 
       [_tasksByRequestID removeObjectForKey:task.requestID];
     });

Libraries/RCTTest/RCTTestModule.m

@@ -52,7 +52,10 @@ RCT_EXPORT_METHOD(verifySnapshot:(RCTResponseSenderBlock)callback)
 
 RCT_EXPORT_METHOD(sendAppEvent:(NSString *)name body:(nullable id)body)
 {
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wdeprecated-declarations"
   [_bridge.eventDispatcher sendAppEventWithName:name body:body];
+#pragma clang diagnostic pop
 }
 
 RCT_REMAP_METHOD(shouldResolve, shouldResolve_resolve:(RCTPromiseResolveBlock)resolve reject:(RCTPromiseRejectBlock)reject)

Libraries/Settings/RCTSettingsManager.m

@@ -62,9 +62,12 @@ RCT_EXPORT_MODULE()
     return;
   }
 
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wdeprecated-declarations"
   [_bridge.eventDispatcher
    sendDeviceEventWithName:@"settingsUpdated"
    body:RCTJSONClean([_defaults dictionaryRepresentation])];
+#pragma clang diagnostic pop
 }
 
 /**

Libraries/Text/RCTTextView.h

@@ -28,6 +28,7 @@
 @property (nonatomic, assign) NSInteger mostRecentEventCount;
 @property (nonatomic, strong) NSNumber *maxLength;
 
+@property (nonatomic, copy) RCTDirectEventBlock onChange;
 @property (nonatomic, copy) RCTDirectEventBlock onSelectionChange;
 
 - (instancetype)initWithEventDispatcher:(RCTEventDispatcher *)eventDispatcher NS_DESIGNATED_INITIALIZER;

Libraries/Text/RCTTextView.m

@@ -472,7 +472,7 @@ static NSAttributedString *removeReactTagFromString(NSAttributedString *string)
   [self _setPlaceholderVisibility];
   _nativeEventCount++;
 
-  if (!self.reactTag) {
+  if (!self.reactTag || !_onChange) {
     return;
   }
 
@@ -490,8 +490,7 @@ static NSAttributedString *removeReactTagFromString(NSAttributedString *string)
   }
   _previousTextLength = textLength;
   _previousContentHeight = contentHeight;
-
+  _onChange(@{
-  NSDictionary *event = @{
     @"text": self.text,
     @"contentSize": @{
       @"height": @(contentHeight),
@@ -499,8 +498,7 @@ static NSAttributedString *removeReactTagFromString(NSAttributedString *string)
     },
     @"target": self.reactTag,
     @"eventCount": @(_nativeEventCount),
-  };
+  });
-  [_eventDispatcher sendInputEventWithName:@"change" body:event];
 }
 
 - (void)textViewDidEndEditing:(UITextView *)textView

React/Base/RCTEventDispatcher.h

@@ -35,7 +35,6 @@ RCT_EXTERN const NSInteger RCTTextUpdateLagWarningThreshold;
 RCT_EXTERN NSString *RCTNormalizeInputEventName(NSString *eventName);
 
 @protocol RCTEvent <NSObject>
-
 @required
 
 @property (nonatomic, strong, readonly) NSNumber *viewTag;
@@ -60,25 +59,25 @@ RCT_EXTERN NSString *RCTNormalizeInputEventName(NSString *eventName);
 @interface RCTEventDispatcher : NSObject <RCTBridgeModule>
 
 /**
- * Send an application-specific event that does not relate to a specific
+ * Deprecated, do not use.
- * view, e.g. a navigation or data update notification.
  */
-- (void)sendAppEventWithName:(NSString *)name body:(id)body;
+- (void)sendAppEventWithName:(NSString *)name body:(id)body
+__deprecated_msg("Subclass RCTEventEmitter instead");
 
 /**
- * Send a device or iOS event that does not relate to a specific view,
+ * Deprecated, do not use.
- * e.g.rotation, location, keyboard show/hide, background/awake, etc.
  */
-- (void)sendDeviceEventWithName:(NSString *)name body:(id)body;
+- (void)sendDeviceEventWithName:(NSString *)name body:(id)body
+__deprecated_msg("Subclass RCTEventEmitter instead");
 
 /**
- * Send a user input event. The body dictionary must contain a "target"
+ * Deprecated, do not use.
- * parameter, representing the React tag of the view sending the event
  */
-- (void)sendInputEventWithName:(NSString *)name body:(NSDictionary *)body;
+- (void)sendInputEventWithName:(NSString *)name body:(NSDictionary *)body
+__deprecated_msg("Use RCTDirectEventBlock or RCTBubblingEventBlock instead");
 
 /**
- * Send a text input/focus event.
+ * Send a text input/focus event. For internal use only.
  */
 - (void)sendTextEventWithType:(RCTTextEventType)type
                      reactTag:(NSNumber *)reactTag

React/Base/RCTEventDispatcher.m

@@ -126,7 +126,10 @@ RCT_EXPORT_MODULE()
     body[@"key"] = key;
   }
 
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wdeprecated-declarations"
   [self sendInputEventWithName:events[type] body:body];
+#pragma clang diagnostic pop
 }
 
 - (void)sendEvent:(id<RCTEvent>)event

React/Modules/RCTAppState.h

@@ -7,8 +7,8 @@
  * of patent rights can be found in the PATENTS file in the same directory.
  */
 
-#import "RCTBridgeModule.h"
+#import "RCTEventEmitter.h"
 
-@interface RCTAppState : NSObject<RCTBridgeModule>
+@interface RCTAppState : RCTEventEmitter
 
 @end

React/Modules/RCTAppState.m

@@ -16,6 +16,8 @@
 
 static NSString *RCTCurrentAppBackgroundState()
 {
+  RCTAssertMainThread();
+
   static NSDictionary *states;
   static dispatch_once_t onceToken;
   dispatch_once(&onceToken, ^{
@@ -37,26 +39,22 @@ static NSString *RCTCurrentAppBackgroundState()
   NSString *_lastKnownState;
 }
 
-@synthesize bridge = _bridge;
-
 RCT_EXPORT_MODULE()
 
+- (dispatch_queue_t)methodQueue
+{
+  return dispatch_get_main_queue();
+}
+
 #pragma mark - Lifecycle
 
-- (instancetype)init
+- (NSArray<NSString *> *)supportedEvents
 {
-  if ((self = [super init])) {
+  return @[@"appStateDidChange", @"memoryWarning"];
-
-    // Needs to be called on the main thread, as it accesses UIApplication
-    _lastKnownState = RCTCurrentAppBackgroundState();
-  }
-  return self;
 }
 
-- (void)setBridge:(RCTBridge *)bridge
+- (void)startObserving
 {
-  _bridge = bridge;
-
   for (NSString *name in @[UIApplicationDidBecomeActiveNotification,
                            UIApplicationDidEnterBackgroundNotification,
                            UIApplicationDidFinishLaunchingNotification,
@@ -75,19 +73,18 @@ RCT_EXPORT_MODULE()
                                              object:nil];
 }
 
-- (void)handleMemoryWarning
+- (void)stopObserving
-{
-  [_bridge.eventDispatcher sendDeviceEventWithName:@"memoryWarning"
-                                              body:nil];
-}
-
-- (void)dealloc
 {
   [[NSNotificationCenter defaultCenter] removeObserver:self];
 }
 
 #pragma mark - App Notification Methods
 
+- (void)handleMemoryWarning
+{
+  [self sendEventWithName:@"memoryWarning" body:nil];
+}
+
 - (void)handleAppStateDidChange:(NSNotification *)notification
 {
   NSString *newState;
@@ -102,8 +99,8 @@ RCT_EXPORT_MODULE()
 
   if (![newState isEqualToString:_lastKnownState]) {
     _lastKnownState = newState;
-    [_bridge.eventDispatcher sendDeviceEventWithName:@"appStateDidChange"
+    [self sendEventWithName:@"appStateDidChange"
-                                                body:@{@"app_state": _lastKnownState}];
+                       body:@{@"app_state": _lastKnownState}];
   }
 }
 
@@ -115,7 +112,7 @@ RCT_EXPORT_MODULE()
 RCT_EXPORT_METHOD(getCurrentAppState:(RCTResponseSenderBlock)callback
                   error:(__unused RCTResponseSenderBlock)error)
 {
-  callback(@[@{@"app_state": _lastKnownState}]);
+  callback(@[@{@"app_state": RCTCurrentAppBackgroundState()}]);
 }
 
 @end

React/Modules/RCTEventEmitter.m

@@ -9,6 +9,7 @@
 
 #import "RCTEventEmitter.h"
 #import "RCTAssert.h"
+#import "RCTUtils.h"
 #import "RCTLog.h"
 
 @implementation RCTEventEmitter
@@ -21,9 +22,16 @@
   return @"";
 }
 
++ (void)initialize
+{
+  if (self != [RCTEventEmitter class]) {
+    RCTAssert(RCTClassOverridesInstanceMethod(self, @selector(supportedEvents)),
+              @"You must override the `supportedEvents` method of %@", self);
+  }
+}
+
 - (NSArray<NSString *> *)supportedEvents
 {
-  RCTAssert(NO, @"You must override the `supportedEvents` method of %@", [self class]);
   return nil;
 }
 
@@ -32,7 +40,8 @@
   RCTAssert(_bridge != nil, @"bridge is not set.");
 
   if (RCT_DEBUG && ![[self supportedEvents] containsObject:eventName]) {
-    RCTLogError(@"`%@` is not a supported event type for %@", eventName, [self class]);
+    RCTLogError(@"`%@` is not a supported event type for %@. Supported events are: `%@`",
+                eventName, [self class], [[self supportedEvents] componentsJoinedByString:@"`, `"]);
   }
   if (_listenerCount > 0) {
     [_bridge enqueueJSCall:@"RCTDeviceEventEmitter.emit"
@@ -62,7 +71,8 @@
 RCT_EXPORT_METHOD(addListener:(NSString *)eventName)
 {
   if (RCT_DEBUG && ![[self supportedEvents] containsObject:eventName]) {
-    RCTLogError(@"`%@` is not a supported event type for %@", eventName, [self class]);
+    RCTLogError(@"`%@` is not a supported event type for %@. Supported events are: `%@`",
+                eventName, [self class], [[self supportedEvents] componentsJoinedByString:@"`, `"]);
   }
   if (_listenerCount == 0) {
     [self startObserving];

React/Views/RCTComponentData.m

@@ -180,7 +180,10 @@ RCT_NOT_IMPLEMENTED(- (instancetype)init)
           ((void (*)(id, SEL, id))objc_msgSend)(target, setter, [RCTConvert BOOL:json] ? ^(NSDictionary *body) {
             body = [NSMutableDictionary dictionaryWithDictionary:body];
             ((NSMutableDictionary *)body)[@"target"] = weakTarget.reactTag;
+#pragma clang diagnostic push
+#pragma clang diagnostic ignored "-Wdeprecated-declarations"
             [weakManager.bridge.eventDispatcher sendInputEventWithName:RCTNormalizeInputEventName(name) body:body];
+#pragma clang diagnostic pop
           } : nil);
         };