But lets say that you want to have your own environments defined for Development vs Production, using xcconfig files is the best way to do this. But, lets say that you want to make a Production archive - and you need to switch the default value of CURRENT_ENVIRONMENT from Development - this can only be done via the command line arguments.
What would be nice, would be able to create a schema for Production which sets this environment in a pre-build run script phase. Then it would be possible to do an archive from within the Xcode UI.