Create an unique identifier for iOS devices?

Question

Is possible to discover the iOS device identifier, using Xcode. I need to each app downloaded have a unique identifier. I thought in generate random numbers, but they might generate the same number more than once! Anyone have an idea?

Answer 1

In UIDevice class apple has provided method uniqueIdentifier but now its deprecated(for iOS5), In method's documentation you will find how you can use uniqueIdentifier.

Answer 2

I've found a pretty simple way to do this, here's how:

Press COMMAND + N and select Cocoa Touch Class.

Name your class NSString+UUID and hit next.

Then, replace the code in NSString+UUID.h with:

@interface NSString (UUID)

+ (NSString *)uuid;

@end

And in NSString+UUID.m with:

@implementation NSString (UUID)

+ (NSString *)uuid {
    NSString *uuidString = nil;
    CFUUIDRef uuid = CFUUIDCreate(NULL);
    if (uuid) {
        uuidString = (NSString *)CFUUIDCreateString(NULL, uuid);
        CFRelease(uuid);
    }
    return [uuidString autorelease];
}

@end

Now, when you need to get the UUID (i.e: store it using NSUserDefaults when your app loads):

-(BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions{

    NSString *userIdentifierKey = @"user-identifier"
    NSUserDefaults *defaults = [NSUserDefaults standardUserDefaults];

    if ([defaults objectForKey:userIdentifierKey] == nil) {

        NSString *theUUID = [NSString uuid];

        [defaults setObject:theUUID forKey:userIdentifierKey];
        [defaults synchronize];

    }

    // additional application setup...

    return YES;
}