iOS Exception: "Dropbox client already authorized"

I think the confusion comes from my trying to persist the Access Token myself instead of letting DBKeychain do it.  In the Android version, I don't think there was any choice.  If we wanted the Access Token to persist between sessions, we had to store it ourselves in the app Preferences.  But for the iOS version, it appears the only reason to deal with an Access Token in my code is if the Access Token were manually generated externally.  If I understand correctly, the SDK for iOS will automatically persist the Access Token upon a successful OAuth2.  (I was actually getting the Access Token from the DBAuthResult.accessToken.accessToken.  But apparently that is unnecessary?)  Let me know if I should eliminate all explicit references to an Access Token in my application code, as long as I only intend to use Access Tokens that have been generated through the OAuth flow in that app itself.