Concept

A subscriber is the component in Combine that receives values from a publisher.

While a publisher produces data, the subscriber consumes that data and performs some action with it.

Conceptually:

Publisher → Subscriber

The subscriber listens for:

values
completion events

Subscribers are typically attached to publishers using operators like sink.

Example

let publisher = ["A", "B", "C"].publisher

publisher
    .sink(
        receiveCompletion: { completion in
            print("Subscriber received completion:", completion)
        },
        receiveValue: { value in
            print("Subscriber received value:", value)
        }
    )
    .store(in: &cancellables)

This pipeline connects a publisher to a subscriber.

sink Subscriber

sink is the most common built-in subscriber in Combine.

It allows you to provide closures that handle:

received values
completion events

Syntax:

sink(receiveCompletion:receiveValue:)

Example: