没有注册的iOS用户注册/身份验证（使用Parse / Swift）

I'd like to create a user in Parse without asking the user to sign up. It is for a chat app built for iOS in Swift. I've heard that UDID is deprecated so cannot use that to uniquely identify user. I want to identify the user even if he/she reinstalls the app / changes device. I don't necessarily want to know any info on the user (email/mobile/etc), just to authenticate them and identify them with an account.I'd like to create a user in Parse without aski