Generating a unique ID in Objective C

Question

How do we get unique IDs in Objective C. I want to create a unique ID for my session & then generate a ID each time a server call happens. Each time this ID should be unique.

I tried using CFUUID class which gives us a huge unique ID (4FE9D00C-531E-45E8-B10E-11968ACC36E9). I want a unique ID of smaller size.

Any clue?

Why do you need it to be shorter? To ensure it is unique it needs to be pretty long. — David Brown, Jan 11 '12 at 00:17
I need to append session ID with request ID which will make this string a huge one. I will be logging this string on server for any tracking purpose. — Abhinav, Jan 11 '12 at 00:20
Do you need it to be shorter, or do you need it to be unique? — Hot Licks, Jan 11 '12 at 00:44

score 6 · Accepted Answer · edited May 23 '17 at 11:45

6

A guid (by shear combinations) generates a unique id. If it's less characters you want then one option is to base64encode the guid. That allows for 64 possibilities per char instead of 16 (0-9, A-F)

This:

540c2d5f-a9ab-4414-bd36-9999f5388773

Becomes:

Xy0MVKupFES9NpmZ9TiHcw

For example: (C# though) http://www.singular.co.nz/blog/archive/2007/12/20/shortguid-a-shorter-and-url-friendly-guid-in-c-sharp.aspx

Here's a SO post on objective-c encode/decode (look @ Mike Ho post):

How do I do base64 encoding on iphone-sdk?

edited May 23 '17 at 11:45

Community

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answered Jan 11 '12 at 00:17

bryanmac

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I just added some links - one being an objective-c post on base64 encode/decode – bryanmac Jan 11 '12 at 00:25
Yep, i missed that point. Your answer is the correct one then. – nicerobot Jan 11 '12 at 01:05

score 0 · Answer 2 · answered May 01 '16 at 19:16

This was my question too, and I liked the answer, but I would like to let here a code done, and I know this is old, but maybe it can help someone:

// DataWithLength is a byte size of UUID. So 32 bytes = 256 bits string
- (NSString*)generateSecureUUID {

    NSMutableData *data = [NSMutableData dataWithLength:32];

    int result = SecRandomCopyBytes(NULL, 32, data.mutableBytes);

    NSAssert(result == 0, @"Error generating random bytes: %d", errno);

    NSString *base64EncodedData = [data base64EncodedStringWithOptions:0];

    return base64EncodedData;
}

score 0 · Answer 3 · answered Jun 07 '17 at 13:10

0

you may try one of the following

1-

CFUUIDRef udidCFUUIDRef = CFUUIDCreate(NULL);
    NSString *UUIDString_token_name = (NSString *) CFBridgingRelease(CFUUIDCreateString(NULL, udidCFUUIDRef));

2-

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

answered Jun 07 '17 at 13:10

Amr Angry

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Generating a unique ID in Objective C

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