# tryAllSatisfy(_:) Publishes a single Boolean value that indicates whether all received elements pass a given error-throwing predicate. ``` func tryAllSatisfy(_ predicate: @escaping (Self.Output) throws -> Bool) -> Publishers.TryAllSatisfy ``` ## Parameters `predicate` A closure that evaluates each received element. Return `true` to continue, or `false` to cancel the upstream and complete. The closure may throw an error, in which case the publisher cancels the upstream publisher and fails with the thrown error. ## Return Value A publisher that publishes a Boolean value that indicates whether all received elements pass a given predicate. ## Discussion Use the [`tryAllSatisfy(_:)`](/documentation/Combine/Publisher/tryAllSatisfy(_:)) operator to determine if all elements in a stream satisfy a criteria in an error-throwing predicate you provide. When this publisher receives an element, it runs the predicate against the element. If the predicate returns `false`, the publisher produces a `false` value and finishes. If the upstream publisher finishes normally, this publisher produces a `true` value and finishes. If the predicate throws an error, the publisher fails and passes the error to its downstream subscriber. In the example below, an error-throwing predicate tests if each of an integer array publisher’s elements fall into the `targetRange`; the predicate throws an error if an element is zero and terminates the stream. ``` let targetRange = (-1...100) let numbers = [-1, 10, 5, 0] numbers.publisher .tryAllSatisfy { anInt in guard anInt != 0 else { throw RangeError() } return targetRange.contains(anInt) } .sink( receiveCompletion: { print ("completion: \($0)") }, receiveValue: { print ("value: \($0)") } ) // Prints: "completion: failure(RangeError())" ``` With operators similar to [`reduce(_:_:)`](/documentation/Combine/Publisher/reduce(_:_:)), this publisher produces at most one value. > Note: Upon receiving any request greater than zero, this publisher requests unlimited elements from the upstream publisher. --- 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)