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.

Answer 1

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

Answer 2

For Swift 5.0, Use this,

    let uuidRef = CFUUIDCreate(nil)
    let uuidStringRef = CFUUIDCreateString(nil, uuidRef)
    let uuid = uuidStringRef as String? ?? ""

Answer 3

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

Answer 4

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

Answer 5

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

Answer 6

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 the 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.