ViewTransaction

[o-nnerb]

Exploring the idea of allowing a more independent and less condensed implementation, it would be interesting to add a ViewTransaction object of type Publisher and Hashable.

The use case I would like to explore is as follows: we have a "Continue" button and we want to notify externally when it is pressed. Following the TCA model, we continue to call the view store's send method to pass the Action.submit and handle this action in the reducer.

In the .submit case, we could use viewTransaction to notify that the submit happened and something external can occur, even enabling a screen transition outside the rules of TCA.

An example implementation of ViewTransaction could be:

public struct ViewTransaction<Output>: Publisher {

    public typealias Failure = Never

    public init()

    public func callAsFunction(_ destination: Output)
}

Then, in the external view, it is possible to make the following implementation:

var body: some View {
    …
    MoviesView(viewStore: viewStore)
        .onReceive(viewStore.transaction) {
            switch $0 {
            case .submit(let movie):
                submitScene(movie)
            }
        }
}

And then in submitScene, I could do whatever I want within SwiftUI.

The implementation of the State would be as follows:

struct MoviesReducer: ReducerProtocol {

    struct State {

        let transaction = ViewTransaction<MoviesDestination>()
    }

    // code
}