IPv4和IPv6支持

根据当前网络环境（IPv4/IPv6）返回，要访问的服务器的相应格式的ip地址

 NSArray *serverDNSs = [IPAdapter getDNSsWithDormain:Host];
 //Host为域名
        if (!serverDNSs || serverDNSs.count <= 0) {
            NSLog(@"Could not get host address");
        }
  NSString *ipAddr0 = [serverDNSs objectAtIndex:0];

IPAdapter.m

#import "IPAdapter.h"
#include <ifaddrs.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <sys/socket.h>

#include <resolv.h>
#include <dns.h>

#import <sys/sysctl.h>
#import <netinet/in.h>
@implementation IPAdapter

/*!
 * 通过hostname获取ip列表 DNS解析地址
 */
+ (NSArray *)getDNSsWithDormain:(NSString *)hostName{
    NSMutableArray *result = [[NSMutableArray alloc] init];
    NSArray *IPV4DNSs = [self getIPV4DNSWithHostName:hostName];
    if (IPV4DNSs && IPV4DNSs.count > 0) {
        [result addObjectsFromArray:IPV4DNSs];
    }

    //由于在IPV6环境下不能用IPV4的地址进行连接监测
    //所以只返回IPV6的服务器DNS地址
    NSArray *IPV6DNSs = [self getIPV6DNSWithHostName:hostName];
    if (IPV6DNSs && IPV6DNSs.count > 0) {
        [result removeAllObjects];
        [result addObjectsFromArray:IPV6DNSs];
    }

    return [NSArray arrayWithArray:result];
}



+ (NSArray *)getIPV4DNSWithHostName:(NSString *)hostName
{
    const char *hostN = [hostName UTF8String];
    struct hostent *phot;

    @try {
        phot = gethostbyname(hostN);
    } @catch (NSException *exception) {
        return nil;
    }

    NSMutableArray *result = [[NSMutableArray alloc] init];
    int j = 0;
    while (phot && phot->h_addr_list && phot->h_addr_list[j]) {
        struct in_addr ip_addr;
        memcpy(&ip_addr, phot->h_addr_list[j], 4);
        char ip[20] = {0};
        inet_ntop(AF_INET, &ip_addr, ip, sizeof(ip));

        NSString *strIPAddress = [NSString stringWithUTF8String:ip];
        [result addObject:strIPAddress];
        j++;
    }

    return [NSArray arrayWithArray:result];
}


+ (NSArray *)getIPV6DNSWithHostName:(NSString *)hostName
{
    const char *hostN = [hostName UTF8String];
    struct hostent *phot;

    @try {
        /**
         * 只有在IPV6的网络下才会有返回值
         */
        phot = gethostbyname2(hostN, AF_INET6);
    } @catch (NSException *exception) {
        return nil;
    }

    NSMutableArray *result = [[NSMutableArray alloc] init];
    int j = 0;
    while (phot && phot->h_addr_list && phot->h_addr_list[j]) {
        struct in6_addr ip6_addr;
        memcpy(&ip6_addr, phot->h_addr_list[j], sizeof(struct in6_addr));
        NSString *strIPAddress = [self formatIPV6Address: ip6_addr];
        [result addObject:strIPAddress];
        j++;
    }

    return [NSArray arrayWithArray:result];
}
+(NSString *)formatIPV6Address:(struct in6_addr)ipv6Addr{
    NSString *address = nil;

    char dstStr[INET6_ADDRSTRLEN];
    char srcStr[INET6_ADDRSTRLEN];
    memcpy(srcStr, &ipv6Addr, sizeof(struct in6_addr));
    if(inet_ntop(AF_INET6, srcStr, dstStr, INET6_ADDRSTRLEN) != NULL){
        address = [NSString stringWithUTF8String:dstStr];
    }

    return address;
}


+(NSString *)formatIPV4Address:(struct in_addr)ipv4Addr{
    NSString *address = nil;

    char dstStr[INET_ADDRSTRLEN];
    char srcStr[INET_ADDRSTRLEN];
    memcpy(srcStr, &ipv4Addr, sizeof(struct in_addr));
    if(inet_ntop(AF_INET, srcStr, dstStr, INET_ADDRSTRLEN) != NULL){
        address = [NSString stringWithUTF8String:dstStr];
    }

    return address;
}

@end