The window’s first responder.
- macOS 10.0+
The first responder is usually the first object in a responder chain to receive an event or action message. In most cases, the first responder is a view object that the user selects or activates with the mouse or keyboard.
You can use the
first property in custom subclasses of responder classes (
NSView, and subclasses) to determine if an instance of the subclass is currently the first responder. You can also use it to help locate a text field that currently has first-responder status. For more on this subject, see Event Handling Basics. This property is key-value observing compliant.