One approach on iOS is to store unique identifier in the “Keychain” (or iCloud itself) which is data kept in the cloud tied to a user’s Apple ID account. Of course this is only an impediment to a determined stalker (who could create a new Apple ID). But a determined stalker could also use a fake name and get a new phone number.
>One approach on iOS is to store unique identifier in the “Keychain” (or iCloud itself) which is data kept in the cloud tied to a user’s Apple ID account
Wouldn't it be obviously visible because you can see the app/file on icloud?
Also, I'm pretty sure the keychain idea is banned by app store guidelines.
I think you are incorrect. I've looked into my Keychain Access > iCloud on Mac and found some entries that seemlike they were created with the APIs you suggest.
E.g. WizzAir has three entries: `WizzAirLogin.username`, `WizzAirLogin.password` an `WizzAirLogin.firstName`.
Or Spotify stored `com.spotify.login.credentials`, `com.spotify.connect.lastStoredDataKey` and `com.spotify.connect.iplSessionHistoryDataKey`.
See https://stackoverflow.com/questions/25276393/how-to-ban-an-i... for more details.