Recently , I learned that the proper way to review a TestFlight build of an application is such that it exposes that TouchID is not supported in the sandbox environment. The proper way to review an in app purchase for a TestFlight application build is to
1. Clear out the Settings app -> iTunes and App Store -> user account setting
2. Launch the TestFlight app, then attempt the in app purchase
3. Enter your user iTunes user account and password.
4. Verify that the purchase attempt was successful
So the question arises - why clear out the user account setting before attempting the purchase. The reason is that for most users, the user account is associated with the production environment. There is also a sandbox version of your user account. The production environment account is unsupported when used in the sandbox environment for the TestFlight app. The TestFlight sandbox environment detects the use of the production account, logs the user out of the production environment, and presents the iTunes Auth dialog a second time for the user to confirm the purchase in the sandbox environment. By following the sequence of instructions above, the user is not presented with multiple iTunes authentication dialogs when attempting a purchase of a TestFlight build of an in app purchase app. It also explains why TouchID doesn't work for TestFlight builds. TouchID only works with the production user account, not the sandbox version of the production user account. If you would like Touch ID to be supported in the TestFlight environment, this would be an enhancement request to be submitted using the Apple Developer Bug Report web page - http://bugreport.apple.com
rich kubota - rkubota@apple.com
developer technical support CoreOS/Hardware/MFI
