Some sort of Universal Time synchronizer.

Just use NSDate, I would format it out as GMT to keep a consistent time stamp.

 

Do you mean UTC -- ignoring timezone?

Or do you mean synchronized, such that you compensate for devices whose clocks were set manually or have drifted. If so, you need to consider how to send a calibration signal to the devices. Without net access this may not be straightforward

 

iPhones already get their time from the cellular network. And I think iPods/iPad already use SNTP to get their time. The problem is solved, you don't have to solve it.

 

Exactly what problem are you trying to solve?

"Coordinate devices with a time stamp" is far too vague. It also fails to state how accurate the time stamp needs to be, nor explain why that accuracy is necessary.

You haven't said whether the devices are networked or not, either. I'm guessing, "not networked", otherwise you wouldn't be sighing about needing a network connection. So you have an unspecified number of non-networked devices that must still "coordinate" using timestamps, for some unspecified reason and with unspecified accuracy.

Unless you're doing navigation or observation of astronomical phenomena, I don't think a few seconds (or even a few minutes) inaccuracy is going to matter. But since you haven't explained what you're trying to do, that's just a guess.

Have you considered that GPS contains an accurate clock, and perhaps that information is available?


XY Problems
http://www.perlmonks.org/index.pl?node_id=542341
.. you want to do X, and you think Y is the best way of doing it.
.. Instead of asking about X, you ask about Y.

.. How do I use X to accomplish Y?
http://perl.plover.com/Questions3.html

 

Exactly and the way SNTP works the user would have be off network for a long time before the drift was enough to be worried about a "couple of seconds" of accuracy.