Loads the preference pane's user interface into its main view.
- macOS 10.1+
The default implementation loads the main nib file (identified by
main) and calls
assign to set the main view of the preference pane. Returns the main view if successful, or
Subclasses should rarely need to override this method. Override this method if you need to use a non-nib based technique for creating the main view. Call
NSPreference to set the main view of the preference pane before returning. Also call
NSPreference to set the initial, first, and last keyboard focus views, respectively.