Guideline 5.1.2 - Legal - Privacy - Data Use and Sharing
We found in our review that your app collects user and device information to create a unique identifier for the user's device. Apps that fingerprint the user's device in this way are in violation of the Apple Developer Program License Agreement and are not appropriate for the App Store.
Specifically, your app uses algorithmically converted device and usage data to create a unique identifier in order to track the user. The device information collected by your app may include some of the following: NSLocaleLanguageCode, systemTimeZone, userInterfaceIdiom, NSProcessInfo, and getifaddrs.
Per section 3.3.9 of the Apple Developer Program License Agreement, neither you nor your app can use any permanent, device-based identifier, or any data derived therefrom, for purposes of uniquely identifying a device.
To resolve this issue, remove any functionality from your app that uses algorithmically converted device and usage data to create a unique identifier for the user's device. You should also remove any related code or implemented SDKs that support this functionality.
Please note that attempting to hide or obfuscate code designed to fingerprint the user's device, or otherwise evade the review process, may result in the termination of your Apple Developer Program account. Review the Terms & Conditions of the Apple Developer Program to learn more about our policies regarding termination.