iOS 生成Universally Unique Identif

- (NSString* )uuid{

     CFUUIDRef uuid = CFUUIDCreate( nil );

    CFStringRefuuidString =CFUUIDCreateString(nil, uuid );

    NSString * result = (NSString *)CFBridgingRelease(CFStringCreateCopy( NULL, uuidString));

    CFRelease(uuid);

    CFRelease(uuidString);

    NSLog(@"%@",result);

    return result;

}