[jayfuerstenberg]

Access to MAC addresses will likely never go away.

Also, if you don't need to identify devices per se, you can fallback on a generated GUID which you persist via NSUserDefaults.

It'll identify the user for the lifespan of that app install on the device.

[ryanpetrich]

I suspect access to MAC addresses will go away at some point—it has the same privacy concerns as UDID.