Plist

Property List

Filename extension	.plist
Uniform Type Identifier (UTI)	com.apple.property-list
Developed by	Apple Computer and GNUstep, formerly NeXT
Type of format	Serialization of dictionary objects.

In the OS X, iOS, NeXTSTEP, and GNUstep programming frameworks, property list files are files that store serialized objects. Property list files use the filename extension .plist, and thus are often referred to as p-list files.

Property list files are often used to store a user's settings. They are also used to store information about bundles and applications, a task served by the resource fork in the old Mac OS.

Since the data represented by property lists is somewhat abstract, the underlying file format can be implemented many ways. Namely, NeXTSTEP used one format to represent a property list, and the subsequent GNUstep and Mac OS X frameworks introduced differing formats.

Under NeXTSTEP, property lists were designed to be human-readable and edited by hand, serialized to ASCII in a syntax somewhat like a programming language.

Strings were represented as:

Binary data was represented as:

Arrays were represented as:

And dictionaries were represented as:

One limitation of the original NeXT property list format is that it could not represent an NSValue (number, boolean, etc.) object.

GNUstep adopts the NeXTSTEP format, with a few additions. First, it now supports NSValue objects (which are represented as plain ASCII), and second, it supports NSDate objects (which are serialized as <*DYYYY-MM-DD HH:MM:SS timezone>)

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