I recently used an app to enter a voucher code and then redeem it to get free stuff. But it only allows 1 code/ phone. I was wondering, what do the iOS apps use when identifying a phone/user?

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    There could be multiple ways to accomplish the same idea. It really depends upon how clever the programmers are for each individual app as well as which version of iOS you are running and potentially which hardware you are running. Is there a practical problem you are seeking to answer or just looking for general discussion? – bmike Oct 7 '14 at 16:57
  • I was interested how it works in general.. but I do have a specific application as well- McDonalds. And of course, I was looking for ways to have more free food :D – Mike94 Oct 7 '14 at 17:29

There are a number of methods an app can use to uniquely identify a device or user.

Transitory (persistent whilst app is installed)



  • alright, great. Thanks for the answer.. so is there actually a way to 'fool' the app that I am using a different phone? I already tried changing my MAC address, my UDID and my app store user account.. – Mike94 Oct 7 '14 at 17:47
  • @Mike It depends entirely on which method the app is using. It could even be obtaining your Game Center username and using that! If your device is jailbroken, you may be able to override the method that determines the unique identifier with a tweak such as Flex. – grg Oct 7 '14 at 17:51
  • thanks for the tip. I tried Flex 2, but it doesn't have any options for the McDonald's app. I guess I'll just leave it alone then... but I don't like when technology wins over me :D – Mike94 Oct 7 '14 at 21:40

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