[SOLVED] Swift Combine Cancel Publishers Without AnyCancellable

Swift Combine Cancel Publishers Without AnyCancellable

I have my networking library based on Combine. Anywhere in my app I can make a request and the networking library returns a publisher, it doesn't have access to the AnyCancellable that is created that actually triggers the pipeline. What I need is the ability to cancel all network requests when the use logs out. Is there a way to cancel Combine pipelines from the publisher not the AnyCancellable.

Here is an example:

    var subscribers = [AnyCancellable]()
    let url = URL(string:"https://www.apeth.com/pep/manny.jpg")!
    let request: AnyPublisher<UIImage, URLError> = URLSession.shared.dataTaskPublisher(for: url)
        .compactMap { UIImage(data:$0.data) }
        .share()
        .eraseToAnyPublisher()
    
    request
        .sink(receiveCompletion: { _ in
            print("subscription2 completed")
        }, receiveValue: { image in
            print("subscription1 value: \(image.scale)")
        })
        .store(in: &subscribers)
    
    // request.cancel()

I would like to call something like request.cancel() on the publisher so that the receiveValue is never triggered.

Solution

What I need is the ability to cancel all network requests when the use logs out.

I suggest you setup a publisher that emits when the user logs out. Then in your API system, you can use prefix(untilOutputFrom: logoutPublisher).

That way, all your network requests will cancel when the logoutPublisher emits.