Re: [iPhone] How to create a unique string
Re: [iPhone] How to create a unique string
- Subject: Re: [iPhone] How to create a unique string
- From: Michael Ash <email@hidden>
- Date: Thu, 13 May 2010 11:05:01 -0400
On Thu, May 13, 2010 at 10:56 AM, Thomas Davie <email@hidden> 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.
Mike
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