iOS: When refusing contact permission, api does not request it again

[nbsoftware]

Hello,
I've tested the scenario (at least on iOS) where the user refuses the permission for the app to access the address book, and it seems the next time we call GetContactListAsync, it does not ask for it again and only returns an empty list (like for the initial call).
This is problematic.
We cannot determine if the user has accepted the permissions or not versus an empty address book.
Any suggestions?
Thanks

[enisn]

Will be solved with #19