gistfile1.m

-(BOOL)application:(UIApplication *)application 
    didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
// start of your application:didFinishLaunchingWithOptions

// !!!: Use the next line only during beta
// [TestFlight setDeviceIdentifier:[[UIDevice currentDevice] uniqueIdentifier]];

[TestFlight takeOff:@"Insert your Application Token here"];
// The rest of your application:didFinishLaunchingWithOptions method
// ...
}