How to find root definition of #if statement in Swift (Xcode) codebase?

I have been hired in a new project, and there are a few references to #if DEVELOPMENT in the source code. The app has two targets:

1. AppName
2. AppNameDev

The app is linked to two different firebase consoles, with two diff databases, cloud functions, etc. Moreover, the app is linked to one stripe account, one Facebook developer account etc. I am unsure of how to determine where these #if statements are from as they don't allow to be tapped on and able to view the definition..