Informs the current object that the user pressed or released a modifier key (Shift, Control, and so on).
- macOS 10.10+
An object encapsulating information about the modifier-key event.
The default implementation of this method does nothing. Use this method to update the state of your gesture recognizer in whatever way is appropriate.
A gesture recognizer monitors events that occur in its view (and any subviews) but does not take part in the responder chain itself. The gesture recognizer receives events before any views do.