how to resolve hostname from ip address in iOS Objective-C

I'm looking for a way to resolve the hostname of a device in my LAN from its ip address on this LAN. I wrote a program in C which works perfectly on Linux using gethostbyaddr() function. When I tried that on OS X or iOS it doesn't work. It seems that there is a problem with gethostbyaddr() in OS X and iOS. Anyway, if you have another idea to get hostname of remote machine from it's IP in iOS, it'll make my day. This is the code I used: First test: 192.168.0.101 is the ip address of the machine that we are querying for hostname. ``` #include <netdb.h> #include <netinet/in.h> #include <arpa/inet.h> struct hostent *he; struct in_addr ipv4addr; inet_pton(AF_INET, "192.168.0.101", &ipv4addr); he = gethostbyaddr(&ipv4addr, sizeof ipv4addr, AF_INET); printf("Host name: %s\n", he->h_name); ``` This code works well on linux, but it doesn't on OS X nor iOS. Second test: ``` + (NSArray *)hostnamesForAddress:(NSString *)address { // Get the host reference for the given address. struct addrinfo hints; struct addrinfo *result = NULL; memset(&hints, 0, sizeof(hints)); hints.ai_flags = AI_NUMERICHOST; hints.ai_family = PF_UNSPEC; hints.ai_socktype = SOCK_STREAM; hints.ai_protocol = 0; int errorStatus = getaddrinfo([address cStringUsingEncoding:NSASCIIStringEncoding], NULL, &hints, &result); if (errorStatus != 0) return nil; CFDataRef addressRef = CFDataCreate(NULL, (UInt8 *)result->ai_addr, result->ai_addrlen); if (addressRef == nil) return nil; freeaddrinfo(result); CFHostRef hostRef = CFHostCreateWithAddress(kCFAllocatorDefault, addressRef); if (hostRef == nil) return nil; CFRelease(addressRef); BOOL isSuccess = CFHostStartInfoResolution(hostRef, kCFHostNames, NULL); if (!isSuccess) return nil; // Get the hostnames for the host reference. CFArrayRef hostnamesRef = CFHostGetNames(hostRef, NULL); NSMutableArray *hostnames = [NSMutableArray array]; for (int currentIndex = 0; currentIndex < [(NSArray *)hostnamesRef count]; currentIndex++) { [hostnames addObject:[(NSArray *)hostnamesRef objectAtIndex:currentIndex]]; } return hostnames; } ``` This code stucks at CFHostStartInfoResolution returning nil at this point. Thx in advance.