plists

A plist, short for property list, is a structured data file used by Apple platforms to store serialized objects. Plists can be in XML format or a more compact binary format, and they typically use the .plist file extension. They are designed to represent simple data structures such as dictionaries, arrays, strings, numbers, booleans, dates, and binary data.

In practice, a plist often acts as a configuration or preferences store. The top-level container is usually a dictionary, consisting of key–value pairs, where keys are strings and values can be any plist type, including nested dictionaries or arrays. Some plists may use an array as the top-level container. The type of each value is important, with primitive types like string, integer, real (floating point), boolean, date, and data (binary) supported.

Common uses include the Info.plist file in macOS and iOS app bundles, which contains metadata required by the system such as CFBundleIdentifier, CFBundleVersion, and CFBundleName. User preferences are often stored as plists via the UserDefaults system, which can persist data as plist representations on disk.

Plists can be edited with various tools. Xcode provides a dedicated plist editor, while other text editors can edit XML plist files directly. In Swift and Objective-C, there are APIs for reading and writing plist data, such as PropertyListSerialization and the Codable-based encoders/decoders, which allow plist data to be mapped to native data structures.

While plists are flexible for configuration and lightweight data, they are not a general-purpose data interchange format like JSON or XML. They are primarily used within Apple ecosystems for app configuration, preferences, and similar lightweight data storage.