How to identify unique users without using a login system (iOS)

Question

I need to have a way to identify users of my application, but without a login system.

I looked at the UUID, which gives me some of the answer to my problem, but since this is not a real UDID, it is not "really unique": if the user reinstalls the application, he receives a new UUID and this cannot work for me.

Is there a way to get the serial number of the device or something unique? All that I could get from the device without having a user on me to fill in any fields.

Answer 1

After some time, we decided that it was either unreliable, impossible, or really annoying to get a unique user ID without asking to fill out a field and actually register.

Therefore, we decided to use their encrypted phone numbers for the formatter using the following process:

• Request a phone number and international code * (+1, +32, etc.)
• Check phone number integrity programmatically
• If this is satisfactory, ask the user to check with a warning
• If everything is in order, send a PIN code and wait for confirmation.
• If applicable, register in the database.

Username: a formatted phone number (for example, [phone]), and this line is then hashed into SHA-256, and finally, we store this extra-long line in the database and recognize all of them.

If you have any questions, please ask here so I can give some clarification. If you have a better idea, I will still be happy to hear that.

Answer 2

You can try to use a unique random string, which is stored in the user's keystore in iCloud.

So, when the user launches your application for the first time, you see that his iCloud does not save the value, so you create and save it. And the next time the user launches the application, you will see this value and act accordingly.

More importantly, even if the user reinstalls your application or makes a factory reset of the device, you can still identify the user by value in your iCloud.