NSUUID Class Reference

Inherits from
Conforms to
Framework
/System/Library/Frameworks/Foundation.framework
Availability
Available in iOS 6.0 and later.
Declared in
NSUUID.h
Related sample code

Overview

The 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, 0xD7, 0x36, 0x95, 0x0A, 0x4D, 0x6E, 0x12, 0x26, 0x80, 0x3A, 0x00, 0x50, 0xE4, 0xC0, 0x00, 0x67. Because a UUID is expressed simply as an array of bytes, there are no endianness considerations for different platforms.

Tasks

Creating UUIDs

Get UUID Values

Class Methods

UUID

Create and returns a new UUID with RFC 4122 version 4 random bytes.

+ (id)UUID
Return Value

A new UUID object.

Availability
  • Available in iOS 6.0 and later.
Related Sample Code
Declared In
NSUUID.h

Instance Methods

getUUIDBytes:

Returns the UUIDs bytes.

- (void)getUUIDBytes:(uuid_t)uuid
Parameters
uuid

The value of uuid represented as raw bytes.

Availability
  • Available in iOS 6.0 and later.
Declared In
NSUUID.h

init

Create and returns a new UUID with RFC 4122 version 4 random bytes.

- (id)init
Return Value

A new UUID object.

Availability
  • Available in iOS 6.0 and later.
Declared In
NSUUID.h

initWithUUIDBytes:

Creates and returns a new UUID with the given bytes.

- (id)initWithUUIDBytes:(const uuid_t)bytes
Parameters
bytes

Raw UUID bytes to use to create the UUID.

Return Value

A new UUID object.

Availability
  • Available in iOS 6.0 and later.
Declared In
NSUUID.h

initWithUUIDString:

Creates and returns a new UUID from the formatted string.

- (id)initWithUUIDString:(NSString *)string
Parameters
string

The source string containing the UUID. The standard format for UUIDs represented in ASCII is a string punctuated by hyphens, for example 68753A44-4D6F-1226-9C60-0050E4C00067.

Return Value

A new UUID object. Returns nil for invalid strings.

Availability
  • Available in iOS 6.0 and later.
Declared In
NSUUID.h

UUIDString

Returns the UUID as a string.

- (NSString *)UUIDString
Return Value

A string containing a formatted UUID for example E621E1F8-C36C-495A-93FC-0C247A3E6E5F.

Discussion

Use this method to create a string representation of the NSUUID object to compare with a CFUUIDRef.

Availability
  • Available in iOS 6.0 and later.
Declared In
NSUUID.h