Question

I am creating an app where users will be given the opportunity to register with email, password, and all the other common stuff. But it is imperative that the user can only register once. Each user should only be able to register one time, with one email.

I am already using the unique device id to ensure that the user can only create one account for the device they are on. So for example if they reinstall the app, and try to create a new account with a different email, my server will detect that their device id has already been registered.

But my problem is this: if a user who already has an account goes to install the app on a different device, they would be able to register again using a different email. That is bad, because now one user has two accounts; and for what Im doing I can’t allow this.

Is there any foreseeable way to stop situation like this? (thanks in advance)

Answer 1

The simple answer is you can’t. You have no way of knowing the iTunes account of the user who installed your app, so you have no way to tell whether two devices belong to the same user unless the user chooses to let you know (some of the apps I’ve worked on have a ‘link devices’ feature to achieve this.