# Publishers.Contains A publisher that emits a Boolean value when it receives a specific element from its upstream publisher. ``` struct Contains where Upstream : Publisher, Upstream.Output : Equatable ``` ## Topics ### Creating a contains Publisher [`init(upstream:output:)`](/documentation/Combine/Publishers/Contains/init(upstream:output:)) Creates a publisher that emits a Boolean value when it receives a specific element from its upstream publisher. ### Declaring supporting types [`Publishers.Contains.Output`](/documentation/Combine/Publishers/Contains/Output-swift.typealias) The kind of values published by this publisher. [`Publishers.Contains.Failure`](/documentation/Combine/Publishers/Contains/Failure) The kind of errors this publisher might publish. ### Inspecting publisher properties [`upstream`](/documentation/Combine/Publishers/Contains/upstream) The publisher from which this publisher receives elements. [`output`](/documentation/Combine/Publishers/Contains/output-swift.property) The element to match in the upstream publisher. ### Comparing publishers [`==(_:_:)`](/documentation/Combine/Publishers/Contains/==(_:_:)) Returns a Boolean value that indicates whether two publishers are equivalent. --- 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)