# ignoreOutput() Ignores all upstream elements, but passes along the upstream publisher’s completion state (finished or failed). ``` func ignoreOutput() -> Publishers.IgnoreOutput ``` ## Return Value A publisher that ignores all upstream elements. ## Discussion Use the [`ignoreOutput()`](/documentation/Combine/Publisher/ignoreOutput()) operator to determine if a publisher is able to complete successfully or would fail. In the example below, the array publisher (`numbers`) delivers the first five of its elements successfully, as indicated by the [`ignoreOutput()`](/documentation/Combine/Publisher/ignoreOutput()) operator. The operator consumes, but doesn’t republish the elements downstream. However, the sixth element, `0`, causes the error throwing closure to catch a `NoZeroValuesAllowedError` that terminates the stream. ``` struct NoZeroValuesAllowedError: Error {} let numbers = [1, 2, 3, 4, 5, 0, 6, 7, 8, 9] cancellable = numbers.publisher .tryFilter({ anInt in guard anInt != 0 else { throw NoZeroValuesAllowedError() } return anInt < 20 }) .ignoreOutput() .sink(receiveCompletion: {print("completion: \($0)")}, receiveValue: {print("value \($0)")}) // Prints: "completion: failure(NoZeroValuesAllowedError())" ``` The output type of this publisher is . --- Copyright © 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)