Question

I have some data that I export into an XML file and put in a remote FTP Server.

I have to identified each object with a unique attribute, it doesn’t matter wich is, but must be persistent always => it can never change.

I don’t want to create a unique attribute, sequence, serial, etc.

I’m using the objectID but every time I use it a get a new reference.

I know that before the object has been saved, it has a ‘temporal id’, but once it’s saved, it gets the definitive.

I’m not seeing this, never.

When I export, just fetch all data and loop, and always I get a new reference:

NSURL *objectID = [[personalDataObject objectID] URIRepresentation];

// some of id received for the SAME OBJECT (no changes made, saved, ...)
// 61993296
// 62194624

thanks,

r.

edit

I was using %d instead of %@, now the returned data is:

x-coredata://F46F3300-8FED-4876-B0BF-E4D2A9D80913/DataEntered/p1
x-coredata://F46F3300-8FED-4876-B0BF-E4D2A9D80913/DataEntered/p2

Answer 1

I think this maybe a reporting problem. The numbers you show that are supposed to be a URI/UUID are way, way to short.

They should look like:

UUIDs (Universally Unique
Identifiers), also known as GUIDs
(Globally Unique Identifiers) or IIDs
(Interface Identifiers), are 128-bit
values guaranteed to be unique. A UUID
is made unique over both space and
time by combining a value unique to
the computer on which it was
generated—usually the Ethernet
hardware address—and a value
representing the number of
100-nanosecond intervals since October
15, 1582 at 00:00:00.

The standard format for UUIDs
represented in ASCII is a string
punctuated by hyphens, for example
68753A44-4D6F-1226-9C60-0050E4C00067.
The hex representation looks, as you
might expect, like a list of numerical
values preceded by 0x. For example,
0xD7, 0x36, 0x95, 0x0A, 0x4D, 0x6E,
0x12, 0x26, 0x80, 0x3A, 0x00, 0x50,
0xE4, 0xC0, 0x00, 0x67 . To use a
UUID, you simply create it and then
copy the resulting strings into your
header and C language source files.
Because a UUID is expressed simply as
an array of bytes, there are no
endianness considerations for
different platforms.

I think you’re seeing different values because your only getting a piece, and a different piece at that, each time you check the UUID. Represented as a URI, they should look more like a URL. They definitely won’t look like an integer.