There are split opinions and contradictory information about TestFlight.
Some sources say you need to go through the old AdHoc Distribution Process and TestFlight only collects UDIDs for you and then helps you spread your AdHoc Build. The same thing you could do with Email.
Testflight allows you to simplify this process immensely. You just build a normal debug IPA and then put it on TestFlight. They have their own global provisioning profile the users install and run the app with. It's as seamless as mass testing on iPhone can be (Granted, that's not a high bar).
What's the truth? Do I need to mess with AdHoc and UDIDs myself, or is this part done by TestFlight? Do I need to make a normal Debug Build just as if I was building to test on my device, like the quote claims above?
According to this tutorial I do have to mess with the UDIDs myself. No mention of any fancy global Enterprise Profile of TestFlight. Limited to 100 devices.
How does it really work? And what's with that Enterprise signing myth? Can someone debunk that?
You have to mess with UDIDs.
In fact, TestFlight just reads the provisionning profile attached to the ipa you sent. Authorized devices are knwon thanks to that provisionning profile.
I usually use AdHoc profiles, but it should also work with development profiles.