How to detect a user after reinstalling the app-CodePudding

I am creating an iOS and Android App and I want to create a screen where the player can start with a guest account or can connect his account with our own accountsystem.

But my question is: Can I detect a user after the app was uninstalled and installed again?

I know that there is something like the vendor. But this will change.

I know that other apps also can do this.

CodePudding user response：

With the user's permission- have them log into an account. Or provide you with their google of facebook account info. So far as hardware ids, those are discouraged and actively being removed to prevent people from the API to prevent this.

Also remember- that unless the user logs in with an account, you don't really know whether it is the same person. You could know its the same phone, but you don't know if he gave it to his kid sister to play on. Or sold it when he got a new one, and now you've given the new owner access to someone else's account. Also, if you rely on hardware ids you won't know its me when I buy a new phone and download it on that.

So yeah- either have him log in with a username and password, or use a 3rd party signon mechanism like Google or Facebook.

CodePudding user response：

For iOS, there is a recommended approach to do that: by using the DeviceCheck framework. The idea here is that it allows you to persist 2 bits of data across app installations on each device. You can set the first bit to 1 if the user has already installed the app or 0 otherwise. And use the second bit, for example, to check if the user has signed in or not.

The official documentation is pretty good, please check it out. The downside of this approach is that you will also have to do some work on the backend side.

UPDATE:

If you specifically want to detect the account, there is no reliable approach. One of the options is to use identifierForVendor or generate some kind of device fingerprint (for example, by combining the device model, timezone, locale, etc.), but of course, this will not work every time.

Uniquely identifying a device is a security leak, and all platforms are putting serious restrictions on unique persistent identifiers because of privacy concerns.