App works fine on later versions iOS 13 and so on but crash on iOS 12 with below crash

Question

Crash Terminating app due to uncaught exception 'NSInvalidUnarchiveOperationException', reason: 'Could not instantiate class named UINavigationBarAppearance because no class named UINavigationBarAppearance was found; the class needs to be defined in source code or linked in from a library (ensure the class is part of the correct target)' terminating with uncaught exception of type NSException

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Answer 1

UINavigationBarAppearance is only available from iOS 13.

Checkout the documentation here: https://developer.apple.com/documentation/uikit/uinavigationbarappearance

You need to exclude the code using UINavigationBarAppearance for iOS version lower than iOS 13:

if #available(iOS 13.0, *) {
  let navBarAppearance = UINavigationBarAppearance()
  ...
  navigationBarAppearace.standardAppearance = navBarAppearance
}