An object representing a universally unique value that bridges to UUID; use NSUUID when you need reference semantics or other Foundation-specific behavior.
SDKs
- iOS 6.0+
- macOS 10.8+
- tvOS 9.0+
- watchOS 2.0+
Framework
- Foundation
Declaration
class NSUUID : NSObject
Overview
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, 0x, 0x36, 0x95, 0x0A, 0x4D, 0x6E, 0x12, 0x26, 0x80, 0x3A, 0x00, 0x50, 0x, 0x, 0x00, 0x67. Because a UUID is expressed simply as an array of bytes, there are no endianness considerations for different platforms.
The NSUUID class is not toll-free bridged with CoreFoundation’s CFUUID. Use UUID strings to convert between CFUUIDRef and NSUUID, if needed. Two NSUUID objects are not guaranteed to be comparable by pointer value (as CFUUID is); use is to compare two NSUUIDinstances.