NSUUID class creates UUID strings that are to uniquely identify types, interfaces, and other items.
UUIDs (Universally Unique Identifiers), also known as GUIDs (Globally Unique Identifiers) or IIDs (Interface Identifiers), are 128-bit values. UUIDs created by
NSUUID conform to RFC 4122 version 4 and are created with random bytes.
The standard format for UUIDs represented in ASCII is a string punctuated by hyphens, for example
68753A44-4D6F-1226-9C60-0050E4C00067. The hex representation looks, as you might expect, like a list of numerical values preceded by 0x. For example,
0x67. Because a UUID is expressed simply as an array of bytes, there are no endianness considerations for different platforms.
NSUUID class is not toll-free bridged with CoreFoundation’s
CFUUID. Use UUID strings to convert between
NSUUID, if needed. Two
NSUUID objects are not guaranteed to be comparable by pointer value (as
CFUUID is); use
is to compare two