Hey, I've got a source code in XCode which looks like that: #if !(TARGET_IPHONE_SIMULATOR)   NSString *carrierName = nil;   CTTelephonyNetworkInfo *netinfo = [[CTTelephonyNetworkInfo alloc] init];   if (netinfo) {     CTCarrier *carrier = netinfo.serviceSubscriberCellularProviders;     carrierName = carrier.carrierName;   }   if (carrierName) {     info[@"carrierName"] = carrierName;   } #endif       return info; } @end Now I get a warning: "Incompatible pointer types initializing 'CTCarrier *' with an expression of type 'NSDictionary<NSString *,CTCarrier *> * _Nullable'" What does that mean?