[FCM] Add completion handler to subscribe/unsubscribe topic actions

Added functionality not exposed in public header yet. I would leave to next FCM SDK owner to expose this functionality (and follow any required review process).

Bugs:
72701086

1 files changed, 6 insertions, 4 deletions

diff --git a/Firebase/Messaging/FIRMessagingPubSub.m b/Firebase/Messaging/FIRMessagingPubSub.m
index c8293e0..74a5292 100644
--- a/Firebase/Messaging/FIRMessagingPubSub.m
+++ b/Firebase/Messaging/FIRMessagingPubSub.m
@@ -146,16 +146,18 @@ static NSString *const kPendingSubscriptionsListKey =
   }];
 }
 
-- (void)subscribeToTopic:(NSString *)topic {
+- (void)subscribeToTopic:(NSString *)topic
+                 handler:(nullable FIRMessagingTopicOperationCompletion)handler {
   [self.pendingTopicUpdates addOperationForTopic:topic
                                       withAction:FIRMessagingTopicActionSubscribe
-                                      completion:nil];
+                                      completion:handler];
 }
 
-- (void)unsubscribeFromTopic:(NSString *)topic {
+- (void)unsubscribeFromTopic:(NSString *)topic
+                     handler:(nullable FIRMessagingTopicOperationCompletion)handler {
   [self.pendingTopicUpdates addOperationForTopic:topic
                                       withAction:FIRMessagingTopicActionUnsubscribe
-                                      completion:nil];
+                                      completion:handler];
 }
 
 - (void)scheduleSync:(BOOL)immediately {