The most prevalent use of Core Foundation is for passing its own primitive types for data, including raw bytes, Unicode strings, numbers, calendar dates, and UUIDs, as well as collections such as arrays, sets, and dictionaries, to numerous OS X C routines, primarily those that are GUI-related.
; Cocoa/Carbon (Mac OS X/iOS) : The Core Foundation class CFUUIDRef is used to produce and store UUIDs, as well as to convert them to and from CFString/NSString representations.
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Several cross-platform frameworks provide dynamic array implementations for C: CFArray and CFMutableArray in Core Foundation; GArray and GPtrArray in GLib.