On May 13, 2010, at 11:05 AM, Michael Ash <[email protected]> wrote:
> On Thu, May 13, 2010 at 10:56 AM, Thomas Davie <[email protected]> wrote: >> >> On 13 May 2010, at 15:33, Eric Gorr wrote: >> >>> So long as it is ok for the string to be unique for the network the user is >>> on only. From the docs: >>> >>> The ID includes the host name, process ID, and a time stamp, which ensures >>> that the ID is unique for the network. >>> >>> A UUID (Universally Unique Identifier) is entirely unique. >> >> No it's not, as can easily be proven by observing that there are only a >> finite number of 40 character strings. A UUID is probabilistically unique. > > CFUUID includes the MAC address, so unless your MAC address is cloned > or you manage to generate two UUIDs on the same device in the same > 100ns time interval or the calendar rolls over (which will take about > 3700 years), they are entirely unique within the universe of CFUUID > strings. No, it doesn't use the MAC address. MAC addresses are uses as part of type 1 uuids, CFUUID has generated type 4 (random) uuids by default since Tiger, and has always generated type 4 on iPhone. If you look at the source to CF there is a way to force it to generate type 1 uuids, but I doubt that is supported. Louis _______________________________________________ Cocoa-dev mailing list ([email protected]) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to [email protected]
