Allows controls to determine when they should become first responder.
- macOS 10.7+
The first responder.
The event to validate. May be
nilif there is no applicable event.
YES if the control should become first responder, otherwise
Some controls, such as
NSText, should only become first responder when the enclosing NSTableView/NSBrowser indicates that the view can begin editing. It is up to the particular control that wants to be validated to call this method in its
mouse method (or perhaps at another time) to determine if it should attempt to become the first responder or not.
NSBrowser classes implement this to allow first responder status only if the responder is a view in a selected row. It also delays the first responder assignment if a
double may be invoked.
The default implementation returns
YES when there is no
next set, otherwise, it is forwarded up the responder chain.