# publisher A Combine publisher that publishes this instance’s value to each subscriber exactly once, if it has any value at all. ``` var publisher: Optional.Publisher { get } ``` ## Discussion In the following example, the publisher for an `Int?` optional publishes its value once, then finishes normally: ``` let optional1: Int? = 1 optional1.publisher .sink(receiveCompletion: { print("optional1 completed.") }, receiveValue: { print("optional1 = \($0)") } ) // Prints: // optional1 = 1. // optional1 completed. ``` In contrast with the publisher, which always publishes a single value, this publisher might not send any values and instead finish normally if the optional’s `output` is `nil`. In the next example, an `Int?` optional that’s `nil` immediately sends the completion, without producing any values. ``` let optional2: Int? = nil optional2.publisher .sink(receiveCompletion: { print("optional2 completed.") }, receiveValue: { print("optional2 = \($0)") } ) // Prints: // optional2 completed. ``` --- 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)