iOS - How to get the IPv6 DNS IP address? - ios

Question

I can use the code below to get the IPv4 DNS address. With the IPv6 DNS address, res_ninit() can not analyse IPv6 address. Like this, iOS - Get device's DNS server address on IPv6 only network, sin_family is always AF_UNSPEC.
Is there any other solutions to get the IPv6 DNS address? Thanks for help.
+ (void)outPutDNSServers {
res_state res = malloc(sizeof(struct __res_state));
int result = res_ninit(res);
if ( result == 0 ) {
for ( int i = 0; i < res->nscount; i++ ) {
NSString *s = [NSString stringWithUTF8String : inet_ntoa(res->nsaddr_list[i].sin_addr)];
NSLog(#"%#",s);
}
}
else {
NSLog(#"%#",#" res_init result != 0");
}
res_nclose(res);
}
Edit：
I have already solved the problem like below.
+ (void)outPutDNSServers {
res_state res = malloc(sizeof(struct __res_state));
int result = res_ninit(res);
if (result == 0) {
union res_9_sockaddr_union *addr_union = malloc(res->nscount * sizeof(union res_9_sockaddr_union));
res_getservers(res, addr_union, res->nscount);
for (int i = 0; i < res->nscount; i++) {
if (addr_union[i].sin.sin_family == AF_INET) {
char ip[INET_ADDRSTRLEN];
inet_ntop(AF_INET, &(addr_union[i].sin.sin_addr), ip, INET_ADDRSTRLEN);
NSString *dnsIP = [NSString stringWithUTF8String:ip];
NSLog(#"IPv4 DNS IP: %#", dnsIP);
} else if (addr_union[i].sin6.sin6_family == AF_INET6) {
char ip[INET6_ADDRSTRLEN];
inet_ntop(AF_INET6, &(addr_union[i].sin6.sin6_addr), ip, INET6_ADDRSTRLEN);
NSString *dnsIP = [NSString stringWithUTF8String:ip];
NSLog(#"IPv6 DNS IP: %#", dnsIP);
} else {
NSLog(#"Undefined family.");
}
}
}
res_nclose(res);
}