项目中需要获取本机IP并发送到服务器，之前在网上找了一段代码获取ip，模拟器运行正常，但在真机上得到的却是一段乱七八糟的字符串。又在网上找的一段代码，It works：

#define MAXADDRS 32

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

// Function prototypes

void InitAddresses();
void FreeAddresses();
void GetIPAddresses();
void GetHWAddresses();

/*
 *  IPAddress.c
 *
 */

#include "IPAddress.h"
#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 "IPAddress.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);
}

//Somewhere in your code
- (NSString *)deviceIPAdress {
InitAddresses();
GetIPAddresses();
GetHWAddresses();
return [NSString stringWithFormat:@"%s", ip_names[1]];
}

// Implement viewDidLoad to do additional setup after loading the view, typically from a nib.
- (void)viewDidLoad {
    [super viewDidLoad];
    ipAddress.text = [self deviceIPAdress];
}

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