(_ handler: @escaping (Self.Failure) -> P) -> Publishers.Catch where P : Publisher, Self.Output == P.Output ``` ## Parameters `handler` A closure that accepts the upstream failure as input and returns a publisher to replace the upstream publisher. ## Return Value A publisher that handles errors from an upstream publisher by replacing the failed publisher with another publisher. ## Discussion Use `catch()` to replace an error from an upstream publisher with a new publisher. In the example below, the `catch()` operator handles the `SimpleError` thrown by the upstream publisher by replacing the error with a `Just` publisher. This continues the stream by publishing a single value and completing normally. ``` struct SimpleError: Error {} let numbers = [5, 4, 3, 2, 1, 0, 9, 8, 7, 6] cancellable = numbers.publisher .tryLast(where: { guard $0 != 0 else {throw SimpleError()} return true }) .catch({ (error) in Just(-1) }) .sink { print("\($0)") } // Prints: -1 ``` Backpressure note: This publisher passes through `request` and `cancel` to the upstream. After receiving an error, the publisher sends sends any unfulfilled demand to the new `Publisher`. SeeAlso: `replaceError` --- 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)