Apple's Responder Chain offers an alternative to the often-cumbersome Delegate pattern for communication between distant iOS components. This mechanism routes events through a sequence of UIResponder objects, from the initial First Responder up to the application and its delegate. Each object attempts to process the event before passing it up the chain.

Developers leverage the target-action pattern with `UIApplication.shared.sendAction()` to initiate this process. By specifying `nil` as the target, the system searches up the chain for an object—like a UIViewController or UIWindow—that implements the corresponding @objc method. The first responder that handles the action stops the propagation.

However, the responder chain is less known and can be complex to debug. It's not suitable for all event types, such as CoreMotion data. For most use cases, the delegate pattern remains the recommended, more straightforward approach for direct communication between classes.