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?
There are a number of methods an app can use to uniquely identify a device or user.
Transitory (persistent whilst app is installed)
- Unique identifier generated by the app and saved in a property list or other equivalent storage in the app sandbox's Library or Documents folder.
- Hashed login or equivalent to determine user.
- CFUUID (https://developer.apple.com/library/ios/documentation/CoreFoundation/Reference/CFUUIDRef/index.html)
- identifierForVendor (https://developer.apple.com/library/ios/documentation/UIKit/Reference/UIDevice_Class/index.html#//apple_ref/occ/instp/UIDevice/identifierForVendor)
- MAC address of device (not recommended by Apple for these purposes).
- Advertising Identifier (can be reset in Settings; https://developer.apple.com/LIBRARY/ios/documentation/AdSupport/Reference/ASIdentifierManager_Ref/index.html#//apple_ref/occ/instp/ASIdentifierManager/advertisingIdentifier).