Nil is not a valid value for a key in a KeyValueDictionary, and attempting to add it will trigger a #rtErrNilKey (2090) error. You *should* get this error when attempting to remove a nil key. But frequently the key-not-present behavior will happen instead:
For #removeKey:ifAbsent: The ifAbsent block will be executed. For #removeKey:otherwise: The otherwise value will be returned.
Last updated: 10/13/14