What is the use of -[NSUserDefaults registerDefaults:]?

Question

What is the difference between:

[[NSUserDefaults standardUserDefaults] registerDefaults:
  [NSDictionary dictionaryWithObjectAndKey:anObject, @\"something\"]         


        

Answer 1

User Defaults are grouped in domains... registerDefaults is used to add defaults to the registration domain..

You can read about the domains in Preferences and Settings Programming Guide.