Call stopObserving on correct queue

Summary:
Since `dealloc` can be called from any thread, this would result `stopObserving` being called on a different thread/queue than the specified `methodQueue`. We specifically encountered this issue with a module needing the main queue having its `stopObserving` called on a background queue.

Changelog:
[iOS][Fixed] - Call [RCTEventEmitter stopObserving] on specified method queue

Reviewed By: RSNara

Differential Revision: D23821741

fbshipit-source-id: 693c3be6876f863da6dd214a829af2cc13a09c3f

Author: appden

Libraries/NativeAnimation/RCTNativeAnimatedModule.mm

@@ -46,6 +46,7 @@ - (instancetype)init
 
 - (void)invalidate
 {
+  [super invalidate];
   [_nodesManager stopAnimationLoop];
   [self.bridge.eventDispatcher removeDispatchObserver:self];
   [self.bridge.uiManager.observerCoordinator removeObserver:self];

Libraries/NativeAnimation/RCTNativeAnimatedTurboModule.mm

@@ -47,6 +47,7 @@ - (instancetype)init
 
 - (void)invalidate
 {
+  [super invalidate];
   [_nodesManager stopAnimationLoop];
   [self.bridge.eventDispatcher removeDispatchObserver:self];
   [self.bridge.uiManager.observerCoordinator removeObserver:self];

Libraries/Network/RCTNetworking.mm

@@ -168,6 +168,8 @@ - (instancetype)initWithHandlersProvider:(NSArray<id<RCTURLRequestHandler>> * (^
 
 - (void)invalidate
 {
+  [super invalidate];
+
   for (NSNumber *requestID in _tasksByRequestID) {
     [_tasksByRequestID[requestID] cancel];
   }
@@ -680,7 +682,7 @@ - (RCTNetworkTask *)networkTaskWithRequest:(NSURLRequest *)request completionBlo
     @"timeout": @(query.timeout()),
     @"withCredentials": @(query.withCredentials()),
   };
-  
+
   // TODO: buildRequest returns a cancellation block, but there's currently
   // no way to invoke it, if, for example the request is cancelled while
   // loading a large file to build the request body

React/CoreModules/RCTAppState.h

@@ -7,6 +7,6 @@
 
 #import <React/RCTEventEmitter.h>
 
-@interface RCTAppState : RCTEventEmitter <RCTInvalidating>
+@interface RCTAppState : RCTEventEmitter
 
 @end

React/CoreModules/RCTAppState.mm

@@ -99,11 +99,6 @@ - (void)stopObserving
   [[NSNotificationCenter defaultCenter] removeObserver:self];
 }
 
-- (void)invalidate
-{
-  [self stopObserving];
-}
-
 #pragma mark - App Notification Methods
 
 - (void)handleMemoryWarning

React/CoreModules/RCTDevSettings.mm

@@ -202,6 +202,7 @@ - (dispatch_queue_t)methodQueue
 
 - (void)invalidate
 {
+  [super invalidate];
 #if ENABLE_PACKAGER_CONNECTION
   [[RCTPackagerConnection sharedPackagerConnection] removeHandler:_reloadToken];
 #endif

React/CoreModules/RCTWebSocketModule.mm

@@ -53,6 +53,8 @@ - (NSArray *)supportedEvents
 
 - (void)invalidate
 {
+  [super invalidate];
+
   _contentHandlers = nil;
   for (RCTSRWebSocket *socket in _sockets.allValues) {
     socket.delegate = nil;

React/Modules/RCTEventEmitter.h

@@ -12,7 +12,7 @@
  * RCTEventEmitter is an abstract base class to be used for modules that emit
  * events to be observed by JS.
  */
-@interface RCTEventEmitter : NSObject <RCTBridgeModule, RCTJSInvokerModule>
+@interface RCTEventEmitter : NSObject <RCTBridgeModule, RCTJSInvokerModule, RCTInvalidating>
 
 @property (nonatomic, weak) RCTBridge *bridge;
 
@@ -37,6 +37,8 @@
 - (void)startObserving;
 - (void)stopObserving;
 
+- (void)invalidate NS_REQUIRES_SUPER;
+
 - (void)addListener:(NSString *)eventName;
 - (void)removeListeners:(double)count;
 

React/Modules/RCTEventEmitter.m

@@ -78,7 +78,7 @@ - (void)stopObserving
   // Does nothing
 }
 
-- (void)dealloc
+- (void)invalidate
 {
   if (_listenerCount > 0) {
     [self stopObserving];