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

Question

What is the difference between:

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


        

Answer 1

Another way of looking at it is this. If you delete the preferences file from ~/Library/Preferences, the defaults that are set by registerDefaults will be the ones that apply to the application until new preferences are set.