After working through the creating of an entitlements file for posting a build to TestFlight I thought it would be worthwhile to share the process since it has changed in recent versions of XCode.
1. Click on the project in the XCode navigator (left panel).
2. Select the appropriate Target.
3. Select the Summary tab.
4. Scroll down towards the bottom of the Summary panel to the “Entitlements” header.
5. Click the “Enable Entitlements” checkbox to enable entitlements
An entitlements file will automatically be added to the project with the default name of the project
The file name can be changed either in the project tree or in the Summary tab. If you change the file name in the summary tab you will be prompted to create a new entitlements file. At that point there will potentially be two files.