To make a quick integration of TestFlight SDK only needs 3 steps:

1. Download the official TestFlight SDK
2. Create the folder “Assets/Plugins/iOS” under Unity project, and copy TestFlight.h & libTestFlight.a to that folder. Then build iOS project.
3. In file AppController.mm* Add #import "../Libraries/TestFlight.h" to the header file section. Also add [TestFlight takeOff:@"<TeamToken>"];
   at the beginning of method - (BOOL)application:(UIApplication*)application didFinishLaunchingWithOptions:(NSDictionary*)launchOptions

That’s it!