My goal is to show a source of error to user. For now I'm using
You can display localized description to user.
Localized description's core goal is readability so you should use it!
Localized Description :
A string containing the localized description of the error. (read-only) The object in the user info dictionary for the key NSLocalizedDescriptionKey. If the user info dictionary doesn’t contain a value for NSLocalizedDescriptionKey, a default string is constructed from the domain and code.
So, if there is no value for NSLocalizedDescriptionKey is found then it will return string from domain and code!
So, in this kind of case you can manage your own custom messages! You can set some common standard message also like -
server is not responding or
unable to complete request etc!!!