You can see where it places your products by looking at:
Xcode Menu-> Preferences-> Locations
Or, if you have specific project parameters, they will be found by viewing
Xcode Menu-> File-> Project Settings
I think he builds ipas from the products in these places and loads them into the simulator. So you cannot find the actual .ipa, there you will find .app in these places.
If you want ipa. Create an archive. Make an Ad Hoc distribution and save the resulting .ipa to your desktop.
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