NSCoder AppKit Additions Reference
Available in OS X v10.0 and later.
NXColor, a type that dates from pre-OpenStep versions of NEXTSTEP, was a
struct. Its replacement,
NSColor, is a class. The difficulties of converting from a
struct to a class require a special method like
decodeNXColor method becomes part of the
NSCoder class only for applications that use the Application Kit.
Decoding NXColor Structures
– decodeNXColorDeprecated in OS X v10.9