ios Mac 地址获取

//mac address
#include <sys/socket.h> // Per msqr
#include <sys/sysctl.h>
#include <net/if.h>
#include <net/if_dl.h>

//mac address
// Return the local MAC addy
// Courtesy of FreeBSD hackers email list
// Accidentally munged during previous update. Fixed thanks to erica sadun & mlamb.
- (NSString *)macaddress{

    int                 mib[];
    size_t              len;
    char                *buf;
    unsigned char       *ptr;
    struct if_msghdr    *ifm;
    struct sockaddr_dl  *sdl;

    mib[] = CTL_NET;
    mib[] = AF_ROUTE;
    mib[] = ;
    mib[] = AF_LINK;
    mib[] = NET_RT_IFLIST;

    if ((mib[] = if_nametoindex("en0")) == ) {
        printf("Error: if_nametoindex error\n");
        return NULL;
    }

    if (sysctl(mib, , NULL, &len, NULL, ) < ) {
        printf("Error: sysctl, take 1\n");
        return NULL;
    }

    if ((buf = malloc(len)) == NULL) {
        printf("Could not allocate memory. error!\n");
        return NULL;
    }

    if (sysctl(mib, , buf, &len, NULL, ) < ) {
        printf("Error: sysctl, take 2");
        free(buf);
        return NULL;
    }

    ifm = (struct if_msghdr *)buf;
    sdl = (struct sockaddr_dl *)(ifm + );
    ptr = (unsigned char *)LLADDR(sdl);
    NSString *outstring = [NSString stringWithFormat:@"%02X:%02X:%02X:%02X:%02X:%02X",
                           *ptr, *(ptr+), *(ptr+), *(ptr+), *(ptr+), *(ptr+)];
    free(buf);

    return outstring;
}