Guard creation of external signaling controller with background task

Signed-off-by: Marcel Müller <marcel-mueller@gmx.de>

NextcloudTalk/NCSettingsController.m

@@ -458,13 +458,17 @@ NSString * const kDidReceiveCallsFromOldAccount = @"receivedCallsFromOldAccount"
 - (void)setSignalingConfigurationForAccountId:(NSString *)accountId
 {
     NSDictionary *signalingConfiguration = [_signalingConfigutations objectForKey:accountId];
+    NSString *externalSignalingTicket = [signalingConfiguration objectForKey:@"ticket"];
     NSString *externalSignalingServer = nil;
+    
     id server = [signalingConfiguration objectForKey:@"server"];
     if ([server isKindOfClass:[NSString class]] && ![server isEqualToString:@""]) {
         externalSignalingServer = server;
     }
-    NSString *externalSignalingTicket = [signalingConfiguration objectForKey:@"ticket"];
+
     if (externalSignalingServer && externalSignalingTicket) {
+        BGTaskHelper *bgTask = [BGTaskHelper startBackgroundTaskWithName:@"NCSetSignalingConfiguration" expirationHandler:nil];
+
         dispatch_async(dispatch_get_main_queue(), ^{
             NCExternalSignalingController *extSignalingController = [self->_externalSignalingControllers objectForKey:accountId];
             
@@ -475,6 +479,8 @@ NSString * const kDidReceiveCallsFromOldAccount = @"receivedCallsFromOldAccount"
             TalkAccount *account = [[NCDatabaseManager sharedInstance] talkAccountForAccountId:accountId];
             extSignalingController = [[NCExternalSignalingController alloc] initWithAccount:account server:externalSignalingServer andTicket:externalSignalingTicket];
             [self->_externalSignalingControllers setObject:extSignalingController forKey:accountId];
+
+            [bgTask stopBackgroundTask];
         });
     }
 }