On iPad and iPhone it is currently possible to retrieve a unique identifier from the device. This identifier has been used by ad agencies to track users across different apps. This has naturally caused frustration for the users, so Apple has decided to remove this functionality.
Yesterday Apple posted the following notice:
Using Identifiers in Your Apps
March 21, 2013
Starting May 1, the App Store will no longer accept new apps or app updates that access UDIDs. Please update your apps and servers to associate users with the Vendor or Advertising identifiers introduced in iOS 6. You can find more details in theUIDevice Class Reference.
Many daily newspapers are sold as 'Consumable' products - where a generic product identifier is used to identify all products. In order for the customer to be able to re-download a newspaper that he/she has already paid for, we currently associate the purchase with the UDID of the user.
Since Apple is deprecating the use of UDIDs we now have to do something else:
On iOS 6, Apple now has support for a similar identifier, that is unique to the app and the device. For our purpose this is as good as a UDID, so on devices running iOS 6 we will use that.
On iOS 4 and iOS 5 devices we generate our own identifier and store this in the 'keychain' of the device. Storing values in the keychain will prevent the information from being deleted even though the user removes the app and re-installs.
This will allow us to correctly identify previous purchases of daily newspapers. When users upgrade the app we will take their previous identifier and store it (or a scrambled version of it) in the keychain.
With this strategy, Visiolink is able to handle the new situation, and we have taken the necessary steps towards moving away from using UDIDs.
For any questions or concerns, please contact Customer Service at firstname.lastname@example.org or call 0045 70233544