UUID of iPhone Device

Question

I am making a Bluetooth chat app using CoreBluetooth, for which I require the UUID of the device.

I tried out the following ways: https://www.chrisjmendez.com/2018/04/04/how-to-find-your-device-id-uuid-for-iphone-development/

But with this, I am getting UDID not UUID.

let WR_UUID = CBUUID(string: "e67e26af6a591f11d3ff186acd1765b2373a2131")
let WR_PROPERTIES: CBCharacteristicProperties = .write
let WR_PERMISSIONS: CBAttributePermissions = .writeable

This is how my code looks, with UDID. It throwing the following error: String e67e26af6a591f11d3ff186acd1765b2373a2131 does not represent a valid UUID'

How do I get a valid UUID of the device?