How can I subscribe again after finishing with Combine?

Question

After subscribing, I completed the subscription with the send method.
I subscribed again, but it's finished. How can I subscribe again?

import Combine

let subject = PassthroughSubject<String, Never>()

subject
.sink(receiveCompletion: { completion in
    print("Received completion:", completion)
}, receiveValue: { value in
    print("Received value:", value)
})

subject.send("test1")
subject.send(completion: .finished)


subject
.sink(receiveCompletion: { completion in
    print("Received completion:", completion)
}, receiveValue: { value in
    print("Received value:", value)
})

subject.send("test2")

The output result is as follows.

Received value: test1
Received completion: finished
Received completion: finished

How can I get "Received value: test2"?

Answer 1

Once you send a completion, the Publisher is done. So, if you want to subscribe again and get new events, you'll need a new instance of that Publisher.

var subject = PassthroughSubject<String, Never>() //<-- var instead of let

subject
.sink(receiveCompletion: { completion in
    print("Received completion:", completion)
}, receiveValue: { value in
    print("Received value:", value)
})

subject.send("test1")
subject.send(completion: .finished)

subject = PassthroughSubject<String, Never>() //<-- Here

subject
.sink(receiveCompletion: { completion in
    print("Received completion:", completion)
}, receiveValue: { value in
    print("Received value:", value)
})

subject.send("test2")