9. Working with Property Lists
Property lists are a way of storing structured data. You can store two of the standard Foundation collection classes (arrays and dictionaries) in property lists, as well as most of the data types, such as strings, numbers, dates, and so on.
Property lists are intended to be abstract. They are not tied to a particular language or to a particular representation. There are currently three defined serializations for property lists. The oldest is the OpenStep property list format. This is a very dense, human-readable format.
Unfortunately, OS X cannot write the old-style property lists. It can read them, but the specification does not define a way of storing dates, or a few other things, so writing to them does not work. ...