In what form are mechanisms similar to the event emitter pattern implemented in Swift?

In Swift, mechanisms similar to the event emitter pattern are implemented using several approaches:

1. NotificationCenter — allows sending and receiving notifications by event name. Subscribers can listen to these notifications and react to them.

NotificationCenter.default.addObserver(self, selector: #selector(handleEvent), name: .myEvent, object: nil)

NotificationCenter.default.post(name: .myEvent, object: nil)

2. Closures — you can pass closures as event handlers, which are called when a specific event occurs.

3. Delegate — a pattern where an object delegates event handling to another object via a protocol.

4. Combine framework (starting from iOS 13) — a reactive framework that allows subscribing to streams of events and processing them.

Thus, for simple cases, NotificationCenter or delegates are often used, while for more complex reactive scenarios, Combine is employed.