Create a Universally Unique Identifier (UUID)

UUID’s are 128-bit values which are guaranteed to be unique – typically the value is based on a machines ethernet address combined with the current time since October 15, 1582.
UUID’s are string values separated by hyphens, for example, here is how a UUID may look: 13222F23-C76A-7781-0C12-0293E3B34398.
The method below creates a UUID and returns a string representation of the same:

Create UUID

- (NSString *)createUUID
{
  // Create universally unique identifier (object)
  CFUUIDRef uuidObject = CFUUIDCreate(kCFAllocatorDefault);
 
  // Get the string representation of CFUUID object.
  NSString *uuidStr = [(NSString *)CFUUIDCreateString(kCFAllocatorDefault, uuidObject) autorelease];
 
  // If needed, here is how to get a representation in bytes, returned as a structure
  // typedef struct {
  //   UInt8 byte0;
  //   UInt8 byte1;
  //   ...
  //   UInt8 byte15;
  // } CFUUIDBytes;
  CFUUIDBytes bytes = CFUUIDGetUUIDBytes(uuidObject);
 
  CFRelease(uuidObject);
 
  return uuidStr;
}