Check out example codes for "Xcode / iOS: How to determine whether code is running in DEBUG / RELEASE build?". It will help you in understanding the concepts better.

Code Example 1

// #if DEBUG will pass in ANY development/ad-hoc build, device or simulator. It's only false for App Store and TestFlight builds.

// Example:

   print("Not App Store build")
   print("App Store build")

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