# SCPreferences ## Overview The `SCPreferences` programming interface allows an application to load and store XML configuration data in a controlled manner and provide the necessary notifications to other applications that need to be aware of configuration changes. To access configuration preferences, you must first establish a preferences session using the [`SCPreferencesCreate(_:_:_:)`](/documentation/SystemConfiguration/SCPreferencesCreate(_:_:_:)) function. To identify a specific set of preferences to access, you pass a value in the prefsID parameter. A `NULL` value indicates that the default system preferences are to be accessed. A string that starts with a leading “/” character specifies the absolute path to the file containing the preferences to be accessed. A string that does not start with a leading “/” character specifies a file relative to the default system preferences directory. When you are finished with the preferences session, use the function to release it. ## Topics ### Creating a Preferences Session [`SCPreferencesCreate(_:_:_:)`](/documentation/SystemConfiguration/SCPreferencesCreate(_:_:_:)) Initiates access to the per-system set of configuration preferences. [`SCPreferencesCreateWithAuthorization(_:_:_:_:)`](/documentation/SystemConfiguration/SCPreferencesCreateWithAuthorization(_:_:_:_:)) Initiates access to the per-system set of configuration preferences with the specified authorization. ### Getting Information About a Preferences Session [`SCPreferencesGetTypeID()`](/documentation/SystemConfiguration/SCPreferencesGetTypeID()) Returns the type identifier of all `SCPreferences` instances. [`SCPreferencesCopyKeyList(_:)`](/documentation/SystemConfiguration/SCPreferencesCopyKeyList(_:)) Returns the currently defined preference keys. [`SCPreferencesGetSignature(_:)`](/documentation/SystemConfiguration/SCPreferencesGetSignature(_:)) Returns a value that can be used to determine if the saved configuration preferences have changed. ### Adding, Getting, and Removing Values [`SCPreferencesAddValue(_:_:_:)`](/documentation/SystemConfiguration/SCPreferencesAddValue(_:_:_:)) Associates the specified value with the specified preference key. [`SCPreferencesGetValue(_:_:)`](/documentation/SystemConfiguration/SCPreferencesGetValue(_:_:)) Retrieves the value associated with the specified preference key. [`SCPreferencesSetValue(_:_:_:)`](/documentation/SystemConfiguration/SCPreferencesSetValue(_:_:_:)) Updates the data associated with the specified preference key with the specified value. [`SCPreferencesRemoveValue(_:_:)`](/documentation/SystemConfiguration/SCPreferencesRemoveValue(_:_:)) Removes the data associated with the specified preference key. ### Applying and Committing Changes [`SCPreferencesApplyChanges(_:)`](/documentation/SystemConfiguration/SCPreferencesApplyChanges(_:)) Requests that the currently stored configuration preferences be applied to the active configuration. [`SCPreferencesCommitChanges(_:)`](/documentation/SystemConfiguration/SCPreferencesCommitChanges(_:)) Commits changes made to the configuration preferences to persistent storage. [`SCPreferencesSynchronize(_:)`](/documentation/SystemConfiguration/SCPreferencesSynchronize(_:)) Synchronizes accessed preferences with committed changes. ### Managing Notifications and Callbacks [`SCPreferencesSetCallback(_:_:_:)`](/documentation/SystemConfiguration/SCPreferencesSetCallback(_:_:_:)) Assigns the specified callback to the specified preferences session. [`SCPreferencesScheduleWithRunLoop(_:_:_:)`](/documentation/SystemConfiguration/SCPreferencesScheduleWithRunLoop(_:_:_:)) Schedules commit and apply notifications for the specified preferences session using the specified run loop and mode. [`SCPreferencesUnscheduleFromRunLoop(_:_:_:)`](/documentation/SystemConfiguration/SCPreferencesUnscheduleFromRunLoop(_:_:_:)) Unschedules commit and apply notifications for the specified preferences session from the specified run loop and mode. [`SCPreferencesSetDispatchQueue(_:_:)`](/documentation/SystemConfiguration/SCPreferencesSetDispatchQueue(_:_:)) Schedules commit and apply notifications for the specified preferences session using the specified dispatch queue. ### Managing Access to a Preferences Session [`SCPreferencesLock(_:_:)`](/documentation/SystemConfiguration/SCPreferencesLock(_:_:)) Locks access to the configuration preferences. [`SCPreferencesUnlock(_:)`](/documentation/SystemConfiguration/SCPreferencesUnlock(_:)) Releases exclusive access to the configuration preferences. ### Data Types [`SCPreferences`](/documentation/SystemConfiguration/SCPreferences) The handle to an open preferences session for accessing system configuration preferences. [`SCPreferencesContext`](/documentation/SystemConfiguration/SCPreferencesContext) A structure containing user-specified data and callbacks for accessing system configuration preferences. [`SCPreferencesCallBack`](/documentation/SystemConfiguration/SCPreferencesCallBack) Type of the callback function used when the preferences have been updated or applied. ### Constants [`SCPreferencesNotification`](/documentation/SystemConfiguration/SCPreferencesNotification) The type of notification (used with the [`SCPreferencesCallBack`](/documentation/SystemConfiguration/SCPreferencesCallBack) callback). --- Copyright © 2026 Apple Inc. 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