How to generate UUID in ios

Question

How to get a UUID in objective c, like in Java UUID is used to generate unique random numbers which represents 128 bit value.

possible duplicate of How to create a GUID/UUID using the iPhone SDK — Basil Bourque, May 21 '14 at 23:31

Basil Bourque · Accepted Answer · 2014-05-21 23:47:35Z

Try:

CFUUIDRef udid = CFUUIDCreate(NULL);
NSString *udidString = (NSString *) CFUUIDCreateString(NULL, udid);

UPDATE:

As of iOS 6, there is an easier way to generate UUID. And as usual, there are multiple ways to do it:

Create a UUID string:

NSString *uuid = [[NSUUID UUID] UUIDString];

Create a UUID:

[[NSUUID UUID]; // which is same as..
[[NSUUID] alloc] init];

Creates an object of type NSConcreteUUID and can be easily casted to NSString, and looks like this: BE5BA3D0-971C-4418-9ECF-E2D1ABCB66BE

NOTE from the Documentation:

Note: The NSUUID class is not toll-free bridged with CoreFoundation’s CFUUIDRef. Use UUID strings to convert between CFUUID and NSUUID, if needed. Two NSUUID objects are not guaranteed to be comparable by pointer value (as CFUUIDRef is); use isEqual: to compare two NSUUID instances.

If you are using iOS 6, you can use NSUUID: NSString * uuid = [[NSUUID UUID] UUIDString]; — Eli Burke, Jul 25 '13 at 12:58
on line 1, CFUUIDRef udid should probably be CFUUIDRef uuid to avoid potential confusion of UDID (Unique Device Identifier) with UUID (Universally Unique Identifier) — CgodLEY, Apr 23 '14 at 15:47

Community · Answer 2 · 2017-05-23 11:55:07Z

Swift version of Raptor's answer:

let uuid = NSUUID().UUIDString

Pang · Answer 3 · 2017-08-11 08:01:53Z

+ (NSString *)uniqueFileName
{
    CFUUIDRef theUniqueString = CFUUIDCreate(NULL);
    CFStringRef string = CFUUIDCreateString(NULL, theUniqueString);
    CFRelease(theUniqueString);
    return [(NSString *)string autorelease];
}

You really shouldn't just leave code without explanation, no matter how straightforward it is — Sirens, Jun 4 '14 at 17:26
Errr, not sure why you selected my particular reply to comment on a year and a half later XD. — Bergasms, Jun 5 '14 at 1:23
I didn't realize it was 1.5 years old.. Oh well, it does work nicely though.. :) — Sirens, Jun 5 '14 at 2:54

Dominic Sander · Answer 4 · 2013-01-16 06:30:51Z

-(NSString*) myUUID()
{
    CFUUIDRef newUniqueID = CFUUIDCreate(kCFAllocatorDefault);
    CFStringRef newUniqueIDString = CFUUIDCreateString(kCFAllocatorDefault, newUniqueID);
    NSString *guid = (__bridge NSString *)newUniqueIDString;
    CFRelease(newUniqueIDString);
    CFRelease(newUniqueID);
    return([guid lowercaseString]);
}

Fabio Caccamo · Answer 5 · 2014-10-07 10:02:15Z

I suggest you to check this library: https://github.com/fabiocaccamo/FCUUID

It provides very simple API to get universally unique identifiers with different persistency levels.

It is compatible with: iOS5, iOS6, iOS7, iOS8

Veeru Sharma · Answer 6 · 2013-08-06 19:19:06Z

you can use CFUUID for iOS 5 or lower version and NSUUID for iOS 6 and 7. for making it more secure you can store your UUID in keychain

Sargis Gevorgyan · Answer 7 · 2017-01-30 13:56:53Z

- (NSString*)generateGUID{
    CFUUIDRef theUUID = CFUUIDCreate(NULL);
    CFStringRef string = CFUUIDCreateString(NULL, theUUID);
    CFRelease(theUUID);
    return [NSString stringWithFormat:@"%@", string];
}

Code-only answers aren't useful for the community. Please look at How to Answer — JimHawkins, Jan 30 '17 at 15:34

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How to generate UUID in ios

How to generate UUID in ios

7 Answers