This article only provides a very brief overview on the entire process, however if people would like I will write a more detailed article.
If you would like to use a shortcut you could just buy this plugin for Unity for $50.00. I’m not associated with the plugin however it does seem to save a LOT of time.
What is TestFlight?
It’s your saviour in a short description. In a slightly longer one however it is an over-the-air app distribution service that is provided for free by TestFlight App, Inc. It allows you invite your testers (or in some cases your clients) onto the service and register their iOS devices (Sorry, no Android as yet!).
Once they are registered you can take their UDID of their device by simply going to the site and clicking their username in the “People” section of the site, this will then pop-up a nice little box with all their details plus an export button that outputs an Apple-ready device ID list.
Putting it all together
When it comes to building the application, do as you would a normal build however after compiling hit Build > Archive. Once it’s finished archiving the organiser window of XCode will open up with the new archive, from here you have to click the button “Distribute” and then select “Save for Enterprise or Ad-Hoc Deployment”.
Make sure that your Code Signing Identity is set to the right application provisioning profile (And if your building for enterprise account’s, make sure the provisioning profile is set within the XCode project itself too!)
The window will then have a spinning icon, once this has vanished it will prompt you for the directory to save the “IPA” file in. Now for the nice bit..
Go to the TestFlight site, press the plus button in the top right of the site, and press upload build. Fill out the form, upload the file and then select which users can use the app. These users will have to be the same devices that users that have their devices registered on the app provisioning profile.