---
title: "timeout(_:scheduler:options:customError:)"
framework: combine
role: symbol
role_heading: Instance Method
path: "combine/publisher/timeout(_:scheduler:options:customerror:)"
---

# timeout(_:scheduler:options:customError:)

Terminates publishing if the upstream publisher exceeds the specified time interval without producing an element.

## Declaration

```swift
func timeout<S>(_ interval: S.SchedulerTimeType.Stride, scheduler: S, options: S.SchedulerOptions? = nil, customError: (() -> Self.Failure)? = nil) -> Publishers.Timeout<Self, S> where S : Scheduler
```

## Parameters

- `interval`: The maximum time interval the publisher can go without emitting an element, expressed in the time system of the scheduler.
- `scheduler`: The scheduler on which to deliver events.
- `options`: Scheduler options that customize the delivery of elements.
- `customError`: A closure that executes if the publisher times out. The publisher sends the failure returned by this closure to the subscriber as the reason for termination.

## Return Value

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

## Discussion

Discussion Use timeout(_:scheduler:options:customError:) to terminate a publisher if an element isn’t delivered within a timeout interval you specify. In the example below, a PassthroughSubject publishes String elements and is configured to time out if no new elements are received within its TIME_OUT window of 5 seconds. A single value is published after the specified 2-second WAIT_TIME, after which no more elements are available; the publisher then times out and completes normally. var WAIT_TIME : Int = 2 var TIMEOUT_TIME : Int = 5

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

DispatchQueue.main.asyncAfter(deadline: .now() + .seconds(WAIT_TIME),                               execute: { subject.send("Some data - sent after a delay of \(WAIT_TIME) seconds") } )

// Prints: value: Some data - sent after a delay of 2 seconds at 2020-03-10 23:47:59 +0000 //         completion: finished at 2020-03-10 23:48:04 +0000 If customError is nil, the publisher completes normally; if you provide a closure for the customError argument, the upstream publisher is instead terminated upon timeout, and the error is delivered to the downstream.

## See Also

### Controlling timing

- [measureInterval(using:options:)](combine/publisher/measureinterval(using:options:).md)
- [debounce(for:scheduler:options:)](combine/publisher/debounce(for:scheduler:options:).md)
- [delay(for:tolerance:scheduler:options:)](combine/publisher/delay(for:tolerance:scheduler:options:).md)
- [throttle(for:scheduler:latest:)](combine/publisher/throttle(for:scheduler:latest:).md)