Observer.m

 //Trigger observer to perform UI update like refresh listing in App
 dispatch_async(dispatch_get_main_queue(), ^(void) {
        [[NSNotificationCenter defaultCenter] postNotificationName:@"productListUpdatedWithProductsList" object:nil];
    });
    
    //Adding observer in listner Class in ViewDidLoad() 
   [[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(reloadFriendRequestSent) name:@"productListUpdatedWithProductsList" object:nil];