feat(messaging, ios): Background Completion Handler from JS

Author: Beat-YT

packages/messaging/ios/RNFBMessaging/RNFBMessaging+AppDelegate.h

@@ -27,6 +27,8 @@ NS_ASSUME_NONNULL_BEGIN
 @property _Nullable RCTPromiseResolveBlock registerPromiseResolver;
 @property(nonatomic, strong) NSCondition *conditionBackgroundMessageHandlerSet;
 @property(nonatomic) BOOL backgroundMessageHandlerSet;
+@property(nonatomic, copy) void (^completionHandler)(UIBackgroundFetchResult);
+@property(nonatomic, assign) UIBackgroundTaskIdentifier backgroundTaskId;
 
 + (_Nonnull instancetype)sharedInstance;
 

packages/messaging/ios/RNFBMessaging/RNFBMessaging+AppDelegate.m

@@ -156,30 +156,34 @@ - (void)application:(UIApplication *)application
     DLog(@"didReceiveRemoteNotification gcm.message_id was present %@", userInfo);
 
     if ([UIApplication sharedApplication].applicationState == UIApplicationStateBackground) {
+      // Store the completion handler to call later when the JS code finishes
+      RNFBMessagingAppDelegate *sharedInstance = [RNFBMessagingAppDelegate sharedInstance];
+      sharedInstance.completionHandler = completionHandler;
+
       // If app is in background state, register background task to guarantee async queues aren't
       // frozen.
-      UIBackgroundTaskIdentifier __block backgroundTaskId =
-          [application beginBackgroundTaskWithExpirationHandler:^{
-            if (backgroundTaskId != UIBackgroundTaskInvalid) {
-              [application endBackgroundTask:backgroundTaskId];
-              backgroundTaskId = UIBackgroundTaskInvalid;
-            }
-          }];
-      // TODO add support in a later version for calling completion handler directly from JS when
-      // user JS code complete
+      sharedInstance.backgroundTaskId = [application beginBackgroundTaskWithExpirationHandler:^{
+        if (backgroundTaskId != UIBackgroundTaskInvalid) {
+          [application endBackgroundTask:backgroundTaskId];
+          backgroundTaskId = UIBackgroundTaskInvalid;
+        }
+      }];
+
       dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(25 * NSEC_PER_SEC)),
                      dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0), ^{
-                       completionHandler(UIBackgroundFetchResultNewData);
+                       if (sharedInstance.completionHandler) {
+                         sharedInstance.completionHandler(UIBackgroundFetchResultNewData);
+                         sharedInstance.completionHandler = nil;
+                       }
 
                        // Stop background task after the longest timeout, async queue is okay to
                        // freeze again after handling period
-                       if (backgroundTaskId != UIBackgroundTaskInvalid) {
-                         [application endBackgroundTask:backgroundTaskId];
-                         backgroundTaskId = UIBackgroundTaskInvalid;
+                       if (sharedInstance.backgroundTaskId != UIBackgroundTaskInvalid) {
+                         [application endBackgroundTask:sharedInstance.backgroundTaskId];
+                         sharedInstance.backgroundTaskId = UIBackgroundTaskInvalid;
                        }
                      });
 
-      RNFBMessagingAppDelegate *sharedInstance = [RNFBMessagingAppDelegate sharedInstance];
       [sharedInstance.conditionBackgroundMessageHandlerSet lock];
       @try {
         DLog(@"didReceiveRemoteNotification sharedInstance.backgroundMessageHandlerSet = %@",

packages/messaging/ios/RNFBMessaging/RNFBMessagingModule.m

@@ -219,6 +219,19 @@ - (NSDictionary *)constantsToExport {
   return resolve(@([RCTConvert BOOL:@(notifCenter.isHeadless)]));
 }
 
+RCT_EXPORT_METHOD(completeNotificationProcessing) {
+  RNFBMessagingAppDelegate *appDelegate = [RNFBMessagingAppDelegate sharedInstance];
+  if (appDelegate.completionHandler) {
+    appDelegate.completionHandler(UIBackgroundFetchResultNewData);
+    appDelegate.completionHandler = nil;
+  }
+
+  if (appDelegate.backgroundTaskId != UIBackgroundTaskInvalid) {
+    [[UIApplication sharedApplication] endBackgroundTask:appDelegate.backgroundTaskId];
+    appDelegate.backgroundTaskId = UIBackgroundTaskInvalid;
+  }
+}
+
 RCT_EXPORT_METHOD(requestPermission
                   : (NSDictionary *)permissions
                   : (RCTPromiseResolveBlock)resolve

packages/messaging/lib/index.js

@@ -98,7 +98,13 @@ class FirebaseMessagingModule extends FirebaseModule {
           return Promise.resolve();
         }
 
-        return backgroundMessageHandler(remoteMessage);
+        // Ensure the handler is a promise
+        const handlerPromise = Promise.resolve(backgroundMessageHandler(remoteMessage));
+        handlerPromise.finally(() => {
+          this.native.completeNotificationProcessing();
+        });
+
+        return handlerPromise;
       });
 
       this.emitter.addListener('messaging_settings_for_notification_opened', remoteMessage => {