What to use if not "IPHONE UDID"?

Question

Wow... look at all the "panic stories" online this week regarding using an iPhone's UDID.

 [[UIDevice currentDevice] uniqueIdentifier]

What SHOULD we be using instead?

What if the phone is sold to another user... and an app has stored some data on a remote server, based on the phone's UDID?

(Of course, I want to avoid the problems with the app store's "encryption restrictions".)

Answer 1

Why not use the Mac Address and possibly then hash it up.

There is an excellent UIDevice-Extension Category here

    - (NSString *) macaddress
{
    int                 mib[6];
    size_t              len;
    char                *buf;
    unsigned char       *ptr;
    struct if_msghdr    *ifm;
    struct sockaddr_dl  *sdl;

    mib[0] = CTL_NET;
    mib[1] = AF_ROUTE;
    mib[2] = 0;
    mib[3] = AF_LINK;
    mib[4] = NET_RT_IFLIST;

    if ((mib[5] = if_nametoindex("en0")) == 0) {
        printf("Error: if_nametoindex error\n");
        return NULL;
    }

    if (sysctl(mib, 6, NULL, &len, NULL, 0) < 0) {
        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, 6, buf, &len, NULL, 0) < 0) {
        printf("Error: sysctl, take 2");
        return NULL;
    }

    ifm = (struct if_msghdr *)buf;
    sdl = (struct sockaddr_dl *)(ifm + 1);
    ptr = (unsigned char *)LLADDR(sdl);
    NSString *outstring = [NSString stringWithFormat:@"%02X:%02X:%02X:%02X:%02X:%02X", 
                           *ptr, *(ptr+1), *(ptr+2), *(ptr+3), *(ptr+4), *(ptr+5)];
    // NSString *outstring = [NSString stringWithFormat:@"%02X%02X%02X%02X%02X%02X", 
    //                       *ptr, *(ptr+1), *(ptr+2), *(ptr+3), *(ptr+4), *(ptr+5)];
    free(buf);

    return outstring;
}

You could possibly hash this with the model?

Answer 2

As I asked this morning in this post, there are some alternative :

1- first, as Apple recommands, identify per install instead of indentifying per device. Therefore, you can use CFUUIDRef. Example :

NSString *uuid = nil;
CFUUIDRef theUUID = CFUUIDCreate(kCFAllocatorDefault);
if (theUUID) {
  uuid = NSMakeCollectable(CFUUIDCreateString(kCFAllocatorDefault, theUUID));
  [uuid autorelease];
  CFRelease(theUUID);
}

2- If you care about a worldwide unique identifier, so you could store this identifier on iCloud.

3- At last, if you really need an identifier that remains after app re-install (that not occurs so frequently), you can use Keychains (Apple's keychain doc). But will apple team like it ?