NSValidatedUserInterfaceItem
A protocol that a custom class can adopt to manage the automatic enablement of a UI control.
Declaration
protocol NSValidatedUserInterfaceItemOverview
The NSValidatedUserInterfaceItem protocol works with the NSUserInterfaceValidations protocol to enable or disable a control automatically, depending on whether any responder in the responder chain can handle the control’s action method. The NSMenuItem and NSToolbarItem classes implement this protocol.
By conforming to this protocol, your control can participate in this validation mechanism. To validate a control, the application calls validateUserInterfaceItem(_:) for each item in the responder chain, starting with the first responder. If no responder returns true, the item is disabled. For example, a menu item that sends the copy: action message would disable itself if no responder in the responder chain can be copied.