A responder object is an object that can respond to events and handle them. UIResponder is
the base class for all responder objects, also known as, simply, responders. It defines the programmatic interface not only for event handling but for common responder behavior. UIApplication, UIView,
and all UIKit classes that descend from UIView (including UIWindow)
inherit directly or indirectly from UIResponder, and thus their instances are responder objects.
The first responder is the res......
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