# tryContains(where:) Publishes a Boolean value upon receiving an element that satisfies the throwing predicate closure. ``` func tryContains(where predicate: @escaping (Self.Output) throws -> Bool) -> Publishers.TryContainsWhere ``` ## Parameters `predicate` A closure that takes an element as its parameter and returns a Boolean value that indicates whether the element satisfies the closure’s comparison logic. ## Return Value A publisher that emits the Boolean value `true` when the upstream publisher emits a matching value. ## Discussion Use [`tryContains(where:)`](/documentation/Combine/Publisher/tryContains(where:)) to find the first element in an upstream that satisfies the error-throwing closure you provide. This operator consumes elements produced from the upstream publisher until the upstream publisher either: - Produces a matching element, after which it emits `true` and the publisher finishes normally. - Emits `false` if no matching element is found and the publisher finishes normally. If the predicate throws an error, the publisher fails, passing the error to its downstream. In the example below, the [`tryContains(where:)`](/documentation/Combine/Publisher/tryContains(where:)) operator tests values to find an element less than `10`; when the closure finds an odd number, like `3`, the publisher terminates with an `IllegalValueError`. ``` struct IllegalValueError: Error {} let numbers = [3, 2, 10, 5, 0, 9] numbers.publisher .tryContains { if ($0 % 2 != 0) { throw IllegalValueError() } return $0 < 10 } .sink( receiveCompletion: { print ("completion: \($0)") }, receiveValue: { print ("value: \($0)") } ) // Prints: "completion: failure(IllegalValueError())" ``` --- 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)