I\'m installing MyApp on the iOS simulator (Xcode 7, iOS 9) using xcrun simctl install booted MyPath/MyApp.app.
MyApp
xcrun simctl install booted MyPath/MyApp.app
This works as expected and
I had the same problem, but using Xamarin. In Visual Studio I solved it by going to the iOS project properties and under "iOS Build" I changed the "Supported architectures" from "i386" to "i386 + x86_64".
Hopefully you can adapt that to XCode.