Can you explain the mechanism of the ResponderChain?.

Responder Chain in iOS is a mechanism for passing events or messages from one object to another until the event is handled.

Each object in the chain has a reference to the next responder object. If the current object cannot handle the event, it passes it further along the chain.

For example, when a button is pressed, the event is first handled by the button itself; if it cannot handle it, the event is passed to its superview, then further up the view hierarchy to the view controller, and so on.

This allows flexible event handling without tightly coupling to specific objects, and enables reactions to events at different levels of the interface hierarchy.