Any idea why this code works great on iOS 12, and not on iOS 13? DNSServiceRef dnsServiceReference; DNSServiceErrorType dnsServiceQueryError = DNSServiceQueryRecord(&dnsServiceReference, kDNSServiceFlagsForceMulticast | kDNSServiceFlagsTimeout, kDNSServiceInterfaceIndexAny, [arpAddress UTF8String], kDNSServiceType_PTR, kDNSServiceClass_IN, QueryRecordCallback, (__bridge void *)(self)); if (dnsServiceQueryError == kDNSServiceErr_NoError) { DNSServiceErrorType callbackError = DNSServiceSetDispatchQueue(dnsServiceReference, dispatch_get_main_queue()); NSAssert(callbackError == kDNSServiceErr_NoError, @"there was an error!"); }