根据域名动态获取IP地址（iOS）

#include <netdb.h>
#include <sys/socket.h>
#include <arpa/inet.h>

- (NSString*)getIPWithHostName:(const NSString*)hostName {

const char *hostN= [hostName UTF8String];
struct hostent* phot;
@try {
phot = gethostbyname(hostN);
if (phot == nil) {
return nil;
}
}
@catch (NSException *exception) {
return nil;
}

struct in_addr ip_addr;
memcpy(&ip_addr, phot->h_addr_list[0], 4);
char ip[20] = {0};
inet_ntop(AF_INET, &ip_addr, ip, sizeof(ip));

NSString* strIPAddress = [NSString stringWithUTF8String:ip];
return strIPAddress;
}