Localized CNPostalAddress field labels

How can I extract the localized field labels on per-CNPostalAddress instance? For example, if I the following:

let address1 = CNMutablePostalAddress()
address1.isoCountryCode = "US"

let address2 = CNMutablePostalAddress()
address2.isoCountryCode = "CA"

How can I extract the State string from address1 and Province string from address2?