swift - Swift Combine. What is a correct way to return from a block of a timeout handler?

Question

I need to implement a handler for a timeout function in Combine. Let's consider the following code structure:

SomeKindOfPublisher<Bool, Never>()
   .timeout(timeoutInterval, scheduler: backgroundQueue,
      customError: { [weak self] () -> Never in
         ...
         while true {} // This block should not return because of Never
      }

My question is how to avoid a weird line while true {}? I would prefer not to change Never to Error type.

标签： swiftcombine

Answer 1

Not sure if this is what you want, but the best way I found to handle timeout on publishers with no failure (Failure == Never) is to force a specific error type and handle timeout error in the completion.

enum SomeKindOfPublisherError: Error {
    case timeout
}

publisher
    .setFailureType(to: SomeKindOfPublisherError.self)
    .timeout(1, scheduler: backgroundQueue, customError: { .timeout })
    .sink(receiveCompletion: {
        switch $0 {
        case .failure(let error):
            // error is SomeKindOfPublisherError.timeout if timeout error occurs
            print("failure: \(error)")
        case .finished:
            print("finished")
        }
    }, receiveValue: { print($0) })

If think it's strange that the timeout operator doesn't changes the publisher failure type to the custom error on its own, but this is some kind of workaround I found.