The receiver's archive data.
- macOS 10.0–10.13Deprecated
The returned data object is the same one specified as the argument to
init(for. It contains whatever data has been encoded thus far by invocations of the various encoding methods. It is safest not to invoke this method until after
encode has returned. In other words, although it is possible for a class to invoke this method from within its
encode(with:) method, that method must not alter the data.