timeout operator in Combine times out even after an event is published

user_723056 0
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I'm using the timeout operator in Combine, and my understanding was that it would timeout only if a publisher does not publish an event, but it seems to timeout even if a value is published.

From the docs

A publisher that terminates if the specified interval elapses with no events received from the upstream publisher.

import PlaygroundSupport
import Combine
import Foundation

PlaygroundPage.current.needsIndefiniteExecution = true

let subject = PassthroughSubject<String, Never>()
let cancellable = subject
    .timeout(.seconds(5), scheduler: DispatchQueue.main)
    .sink(
          receiveCompletion: { print ("completion: \($0) at \(Date())") },
          receiveValue: { print ("value: \($0) at \(Date())") }
     )

subject.send("Sending data")

/*
Prints
value: Sending data at 2021-01-06 22:41:12 +0000
completion: finished at 2021-01-06 22:41:17 +0000
*/

Is my understanding wrong with the operator?.

combine swift ios
1 Answers

You misunderstood the meaning of the text you quoted. It says that a publisher terminates if the specified interval elapses with no events received, which means, in your example, if there was no value received in the previous 5 seconds.

Documentation also provides a slightly different example that illustrates the point.

So, in other words, if you'd added this to your example:

DispatchQueue.main.async(deadline: .now() + 3) { subject.send("in 3 seconds") }

then you would have had the following output:

value: Sending data at 2021-01-06 22:41:12 +0000
value: in 3 seconds at 2021-01-06 22:41:15 +0000
completion: finished at 2021-01-06 22:41:20 +0000

with the completion arriving 5 seconds after the last value.

user_9681550
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