CFDictionaryRef

CFDictionaryRef is an opaque type in the Core Foundation framework of macOS and iOS that represents a collection of key-value pairs. It is an immutable dictionary, meaning its contents cannot be changed after creation. CFDictionaryRef is part of the Core Foundation family of data types, which are toll-free bridged with their Foundation equivalents, such as NSDictionary. This means that a CFDictionaryRef can often be used where an NSDictionary is expected, and vice versa, in Objective-C and Swift code.

Dictionaries are fundamental data structures for organizing and retrieving data. In a CFDictionaryRef, each value is associated with a unique key. Both keys and values are stored as pointers, and the dictionary manages their memory. When creating a CFDictionaryRef, you must specify the functions used for retaining and releasing the keys and values, as well as a function for comparing keys. This allows CFDictionaryRef to work with any type of data. Common operations include adding elements during creation, retrieving a value associated with a specific key, and iterating through all key-value pairs. CFDictionaryRef is a powerful tool for managing structured data in C-based applications and when working at a lower level of the Apple operating systems.