Is there a method to generate a standard 128bit GUID (UUID) on the Mac?

Question

Is there a built in function equivalent to .NET's

Guid.NewGuid();

in Cocoa?

My desire is to produce a string along the lines of 550e8400-e29b-41d4-a716-446655440000 which represents a unique identifier.

Solution 1

UUIDs are handled in Core Foundation, by the CFUUID library. The function you are looking for is CFUUIDCreate.

FYI for further searches: these are most commonly known as UUIDs, the term GUID isn't used very often outside of the Microsoft world. You might have more luck with that search term.

Solution 2

Some code:

For a string UUID, the following class method should do the trick:

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

if you really want the bytes (not the string):

+(CFUUIDBytes)UUIDBytes {
    CFUUIDRef theUUID = CFUUIDCreate(NULL);
    CFUUIDBytes bytes = CFUUIDGetUUIDBytes(theUUID);
    CFRelease(theUUID);
    return bytes;
}

where CFUUIDBytes is a struct of the UUID bytes.

Solution 3

Since 10.8 you could also use:

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

Solution 4

Check out the Wikipedia article and the Core Foundation page.

Solution 5

You can create an alias in the ~/.bash_profile and call uuid from the terminal:

alias uuid="uuidgen | tr '[:upper:]' '[:lower:]'"

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