What components does the Responder Chain consist of?

Responder Chain in iOS consists of a sequence of objects that can handle user input events (such as touches, key presses). The main components of this chain:

• UIResponder — the base class for objects that can receive events.
• UIView — views that can be handlers.
• UIViewController — controllers managing views.
• UIWindow — the application window, the top level in the hierarchy.
• UIApplication — the application object, the last in the chain.

When an event is not handled by the current object, it is passed to the next object in the chain until it is handled or reaches UIApplication.