Can you explain the mechanism of sequential message processing through the responder chain?

Responder Chain is a mechanism where an event or message is passed along a chain of objects until one of them handles it. In iOS, this is often used for handling touch events or user actions.

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

Example:

• User taps a button
• The event is first received by the UIButton
• If the button does not handle the event, it is passed to its superview
• The event then propagates up the view hierarchy until it is handled or reaches the top level

This allows flexible distribution of event handling and avoids tight coupling to a specific object.