UIDevice uniqueIdentifier deprecated - What to do now?

Question

It has just come to light that the UIDevice uniqueIdentifier property is deprecated in iOS 5 and unavailable in iOS 7 and above. No alternative method or pr

Answer 1

I'm sure Apple have annoyed many people with this change. I develop a bookkeeping app for iOS and have an online service to sync changes made on different devices. The service maintains a database of all devices and the changes that need to be propagated to them. Therefore it's important to know which devices are which. I'm keeping track of devices using the UIDevice uniqueIdentifier and for what it's worth, here are my thoughts.

• Generate a UUID and store in user defaults? No good because this does not persist when the user deletes the app. If they install again later the online service should not create a new device record, that would waste resources on the server and give a list of devices containing the same one two or more times. Users would see more than one "Bob's iPhone" listed if they re-installed the app.

• Generate a UUID and store in the keychain? This was my plan, since it persists even when the app is uninstalled. But when restoring an iTunes backup to a new iOS device, the keychain is transferred if the backup is encrypted. This could lead to two devices containing the same device id if the old and new devices are both in service. These should be listed as two devices in the online service, even if the device name is the same.

• Generate a hash the MAC address and bundle id? This looks like the best solution for what I need. By hashing with the bundle id, the generated device id is not going to enable the device to be tracked across apps and I get a unique ID for the app+device combination.

It's interesting to note that Apple's own documentation refers to validating Mac App Store receipts by computing a hash of the system MAC address plus the bundle id and version. So this seems allowable by policy, whether it passes through app review I don't yet know.