Fix callback crashes - Guarantee that the RN callback is only ever called once (#168)

* Make sure the RN callback is only ever called once

* Fix callback crash on Windows

Author: ndbroadbent

RNSound/RNSound.m

@@ -44,12 +44,13 @@ -(NSString *) getDirectory:(int)directory {
 -(void) audioPlayerDidFinishPlaying:(AVAudioPlayer*)player
                        successfully:(BOOL)flag {
   NSNumber* key = [self keyForPlayer:player];
-  if (key != nil) {
-    @synchronized(key) {
-      RCTResponseSenderBlock callback = [self callbackForKey:key];
-      if (callback) {
-        callback(@[@(flag)]);
-      }
+  if (key == nil) return;
+
+  @synchronized(key) {
+    RCTResponseSenderBlock callback = [self callbackForKey:key];
+    if (callback) {
+      callback(@[@(flag)]);
+      [[self callbackPool] removeObjectForKey:key];
     }
   }
 }

android/src/main/java/com/zmxv/RNSound/RNSoundModule.java

@@ -87,16 +87,24 @@ public void play(final Integer key, final Callback callback) {
       return;
     }
     player.setOnCompletionListener(new OnCompletionListener() {
+      boolean callbackWasCalled = false;
+
       @Override
       public synchronized void onCompletion(MediaPlayer mp) {
         if (!mp.isLooping()) {
+          if (callbackWasCalled) return;
+          callbackWasCalled = true;
           callback.invoke(true);
         }
       }
     });
     player.setOnErrorListener(new OnErrorListener() {
+      boolean callbackWasCalled = false;
+
       @Override
       public synchronized boolean onError(MediaPlayer mp, int what, int extra) {
+        if (callbackWasCalled) return true;
+        callbackWasCalled = true;
         callback.invoke(false);
         return true;
       }

windows/RNSoundModule/RNSoundModule/RNSound.cs

@@ -142,6 +142,7 @@ await CoreApplication.MainView.CoreWindow.Dispatcher.RunAsync(CoreDispatcherPrio
         [ReactMethod]
         public void play(int key, ICallback callback)
         {
+            Boolean callbackWasCalled = false;
             MediaPlayer player = null;
             Debug.WriteLine("play()");
 
@@ -167,6 +168,8 @@ public void play(int key, ICallback callback)
             player.MediaEnded +=
                 delegate
                 {
+                    if (callbackWasCalled) return;
+                    callbackWasCalled = true;
                     Debug.WriteLine("Media Ended");
                     callback.Invoke(true);
                 };