Swift: A nicer way to tell if your app is running in Debug mode

Often while working on an iOS app there’s functionality that you want exposed only when the app is running in a Debug build configuration. Previously I would use build environment variables and preprocessor macros to determine this, but thanks to the great answer on this Stack Overflow question I now use a runtime check to tell whether the app is running in Debug or Release mode:

// Returns true if the app is running in a Debug build
_isDebugAssertConfiguration() -> Bool

// Returns true if the app is running in a Release build
_isReleaseAssertConfiguration() -> Bool

// Example usage: only printing to the log when the app is running in Debug
if _isDebugAssertConfiguration() {
  print("Log: User \(user) logged in")
}

Note: these functions aren’t publicly documented in Swift’s API, and are only available from Swift 2.1 onwards. As kennytm says in his Stack Overflow answer, there is a risk of this function being removed in a future update.

If you do want to use this in your codebase, I have created a convenient helper around the function in my Swift helper library: APSwiftHelpers.