So on iOS 8 we could check that current user IS device owner, because he have exactly the same fingerprint. iOS give us true or false value.
But how can we use this value as PIN-code for App's authorization? For example where could we store user's login and password, which we could read and then use in internet-service?
I believe that in order to use the TOUCH ID for an application is not possible. All the other ios 3rd party applications have their own 3rd party fingerprint scanning software. the TouchID software on ios is unavailable for other apps, for "Security Reasons". And the Security Reasons are that TouchID saves all its fingerprint data in the A7, or A6 chip. and does not give out that information to 3rd party applications.