第一种方法是用系统api的方式获取，如下

    #include <stdio.h>  
    #include <stdlib.h>  
    #include <string.h>  
    #include <unistd.h>  
    #include <sys/ioctl.h>  
    #include <sys/types.h>  
    #include <sys/socket.h>  
    #include <netinet/in.h>  
    #include <netdb.h>  
    #include <arpa/inet.h>  
    #include <sys/sockio.h>  
    #include <net/if.h>  
    #include <errno.h>  
    #include <net/if_dl.h>  

//#include "GetAddresses.h"  
      
#define min(a,b)    ((a) < (b) ? (a) : (b))  
#define max(a,b)    ((a) > (b) ? (a) : (b))  

#define BUFFERSIZE  4000  

char *if_names[MAXADDRS];  
char *ip_names[MAXADDRS];  
char *hw_addrs[MAXADDRS];  
    unsigned long ip_addrs[MAXADDRS];  

static int   nextAddr = 0;  

void InitAddresses()  
    {  
int i;  
for (i=0; i<MAXADDRS; ++i)  
        {  
            if_names[i] = ip_names[i] = hw_addrs[i] = NULL;  
            ip_addrs[i] = 0;  
        }  
    }  

void FreeAddresses()  
    {  
int i;  
for (i=0; i<MAXADDRS; ++i)  
        {  
if (if_names[i] != 0) free(if_names[i]);  
if (ip_names[i] != 0) free(ip_names[i]);  
if (hw_addrs[i] != 0) free(hw_addrs[i]);  
            ip_addrs[i] = 0;  
        }  
        InitAddresses();  
    }  

void GetIPAddresses()  
    {  
int                 i, len, flags;  
char                buffer[BUFFERSIZE], *ptr, lastname[IFNAMSIZ], *cptr;  
struct ifconf       ifc;  
struct ifreq        *ifr, ifrcopy;  
struct sockaddr_in  *sin;  

char temp[80];  

int sockfd;  

for (i=0; i<MAXADDRS; ++i)  
        {  
            if_names[i] = ip_names[i] = NULL;  
            ip_addrs[i] = 0;  
        }  

        sockfd = socket(AF_INET, SOCK_DGRAM, 0);  
if (sockfd < 0)  
        {  
            perror("socket failed");  
return;  
        }  

        ifc.ifc_len = BUFFERSIZE;  
        ifc.ifc_buf = buffer;  

if (ioctl(sockfd, SIOCGIFCONF, &ifc) < 0)  
        {  
            perror("ioctl error");  
return;  
        }  

        lastname[0] = 0;  

for (ptr = buffer; ptr < buffer + ifc.ifc_len; )  
        {  
            ifr = (struct ifreq *)ptr;  
            len = max(sizeof(struct sockaddr), ifr->ifr_addr.sa_len);  
            ptr += sizeof(ifr->ifr_name) + len;  // for next one in buffer  
              
if (ifr->ifr_addr.sa_family != AF_INET)  
            {  
continue;   // ignore if not desired address family  
            }  

if ((cptr = (char *)strchr(ifr->ifr_name, ':')) != NULL)  
            {  
                *cptr = 0;      // replace colon will null  
            }  

if (strncmp(lastname, ifr->ifr_name, IFNAMSIZ) == 0)  
            {  
continue;   /* already processed this interface */  
            }  

            memcpy(lastname, ifr->ifr_name, IFNAMSIZ);  

            ifrcopy = *ifr;  
            ioctl(sockfd, SIOCGIFFLAGS, &ifrcopy);  
            flags = ifrcopy.ifr_flags;  
if ((flags & IFF_UP) == 0)  
            {  
continue;   // ignore if interface not up  
            }  

            if_names[nextAddr] = (char *)malloc(strlen(ifr->ifr_name)+1);  
if (if_names[nextAddr] == NULL)  
            {  
return;  
            }  
            strcpy(if_names[nextAddr], ifr->ifr_name);  

            sin = (struct sockaddr_in *)&ifr->ifr_addr;  
            strcpy(temp, inet_ntoa(sin->sin_addr));  

            ip_names[nextAddr] = (char *)malloc(strlen(temp)+1);  
if (ip_names[nextAddr] == NULL)  
            {  
return;  
            }  
            strcpy(ip_names[nextAddr], temp);  

            ip_addrs[nextAddr] = sin->sin_addr.s_addr;  

            ++nextAddr;  
        }  

        close(sockfd);  
    }  

void GetHWAddresses()  
    {  
struct ifconf ifc;  
struct ifreq *ifr;  
int i, sockfd;  
char buffer[BUFFERSIZE], *cp, *cplim;  
char temp[80];  

for (i=0; i<MAXADDRS; ++i)  
        {  
            hw_addrs[i] = NULL;  
        }  

        sockfd = socket(AF_INET, SOCK_DGRAM, 0);  
if (sockfd < 0)  
        {  
            perror("socket failed");  
return;  
        }  

        ifc.ifc_len = BUFFERSIZE;  
        ifc.ifc_buf = buffer;  

if (ioctl(sockfd, SIOCGIFCONF, (char *)&ifc) < 0)  
        {  
            perror("ioctl error");  
            close(sockfd);  
return;  
        }  

        ifr = ifc.ifc_req;  

        cplim = buffer + ifc.ifc_len;  

for (cp=buffer; cp < cplim; )  
        {  
            ifr = (struct ifreq *)cp;  
if (ifr->ifr_addr.sa_family == AF_LINK)  
            {  
struct sockaddr_dl *sdl = (struct sockaddr_dl *)&ifr->ifr_addr;  
int a,b,c,d,e,f;  
int i;  

                strcpy(temp, (char *)ether_ntoa(LLADDR(sdl)));  
                sscanf(temp, "%x:%x:%x:%x:%x:%x", &a, &b, &c, &d, &e, &f);  
                sprintf(temp, "%02X:%02X:%02X:%02X:%02X:%02X",a,b,c,d,e,f);  

for (i=0; i<MAXADDRS; ++i)  
                {  
if ((if_names[i] != NULL) && (strcmp(ifr->ifr_name, if_names[i]) == 0))  
                    {  
if (hw_addrs[i] == NULL)  
                        {  
                            hw_addrs[i] = (char *)malloc(strlen(temp)+1);  
                            strcpy(hw_addrs[i], temp);  
break;  
                        }  
                    }  
                }  
            }  
            cp += sizeof(ifr->ifr_name) + max(sizeof(ifr->ifr_addr), ifr->ifr_addr.sa_len);  
        }  

        close(sockfd);  
    }  

调用如下：

    - (NSString *)deviceIPAdress {  
        InitAddresses();  
        GetIPAddresses();  
        GetHWAddresses();  

return [NSString stringWithFormat:@"%s", ip_names[1]];  
    }  

这样得到的ip，如果在内网中，那么就是内网的ip.

第二种方法是可以获取公网ip

    - (void)getCurrentIP  
    {  
        NSURL *url = [NSURL URLWithString:@"http://automation.whatismyip.com/n09230945.asp"];  
        __block ASIHTTPRequest *request = [ASIHTTPRequest requestWithURL:url];  
        [request setCompletionBlock:^{  
            NSString *responseString = [request responseString];  
if (responseString) {  

                NSString *ip = [NSString stringWithFormat:@"%@", responseString];  

                NSLog(@"responseString = %@", ip);  
            };  

        }];  

        [request setFailedBlock:^{  
        }];  
    }  

用到了ASIHTTPRequest这个网络开源库。

http://automation.whatismyip.com/n09230945.asp这个http url就可以获取你当前的ip地址。

转载于:https://www.cnblogs.com/ligun123/archive/2011/10/26/2225072.html