[mrgreenfur]

Generating your own UUID is forbidden I thought?

What if apple sandboxed it to each app to make it safer/easier?

[tinus_hn]

You can’t look through device identifiers like the MAC address or the serial to create ids.

[varenc]

since iOS 7 Apple always returns "02:00:00:00:00:00" for the WLAN MAC address for this very reason.

Besides the IDFA Apples seem to have tried hard to get rid of the obvious ways for different apps to link activity between their users. Of course if you login or provide an email it becomes easy...and there's plenty of trickier less reliable ways like looking at IP address