Since Beta3, usage description when NFC scan banner is displayed, is done programmaticaly.
After creating a instance of NFCNDEFReaderSession, you can set the alertMessage.
Hope it helps.
Thank you very much - sorted my problem and very uesful to be able to change dynamically for each scan.
It's cool. And here my another question is "When will the NFCReaderUsageDescription value that I set up in Xcode plist file display?"