Steps:
- obtain the app from App Store (just download it to mobile phone)
- obtain Apple Configurator, this is Apple's application for managing iOS devices for business and schools
- connect iPhone over cable and see it in the Apple Configurator
- add app from your device in Apple Configurator
- in terminal open
Library/Caches/Assets/TemporaryItems
- here you will be able to find .ipa file of your application
Time to inspect .ipa file:
- rename it to .ipa.zip and uncompress zip archive
Have a fun!
What can we get/inspect: assets, libraries other resources related to the application. Good practice is to verify linking with static libraries that can be used in multiples places.