Ordered Property List Encoder for Swift

A custom XML property list encoder for Swift that encodes keys in the same order as they were declared, primarily intended for interoperability with legacy formats.

Background

While the validity of a dictionary from a property list, like an object in JSON, ideally should be unaffected by the order of its keys, some plist-based formats such as the iTunes library XML format have implementations/parsers that depend on keys being 'conveniently' ordered (e.g. the id of the parent playlist is listed before the children). PropertyListEncoder from Foundation unfortunately does not offer this, hence this package.