Preference Domains

When creating a new preference or searching for an existing one, Core Foundation uses the notion of “Preference Domains” to specify the scope and location of the preference. A preference domain consists of three pieces of information, an application ID, a host name, and a user name. Table 1 shows all of the preference domains, listed in the order that they are searched when attempting to locate a preference value.

When using the high-level preferences functions CFPreferencesSetAppValue, and CFPreferencesCopyAppValue, you need only specify the application ID. The first function, CFPreferencesSetAppValue, places the preference value into the “Current User” and “Any Host” domain for the application, meaning that the standard location for application preferences is domain number two as listed in Table 1. The other function, CFPreferencesCopyAppValue, searches through all the domains in order until a value is found. See Using the High-Level Preferences API for information on using these functions.