If the user offload my app from Settings app (to free up storage) and reinstall it, will the identifierForVendor change?
identifierForVendor change when offload app?
Short answer - yes - https://developer.apple.com/documentation/uikit/uidevice/1620059-identifierforvendor
I disagree with MobileTen. I don't think the page that he links to says anything about offloading.
Offloading is a relatively new feature in iOS. If the identifierForVendor changed during offloading, many apps that predated offloading (including one of mine!) would have had problems as a result. I have not seen any such problems, which makes me think that the identifierForVendor does not change. But I could be wrong; users do not always report problems.
Anyone else have any experience to share?
(Of course the safe thing to do is to assume that it can change at any time.)