Publishers.MergeMany sample

FunctionCombine.playground

import Combine

struct ReducerContainer {
    let reducer: () -> (AnyPublisher<Int, Never>)

    init(reducer: @escaping () -> (AnyPublisher<Int, Never>)) {
        self.reducer = reducer
    }

    static func combine(_ reducers: [ReducerContainer]) -> ReducerContainer {
        .init {
            Publishers.MergeMany(
                reducers.map {
                    $0.reducer()
                }
            )
            .eraseToAnyPublisher()
        }
    }
}

let reducerContainer1 = ReducerContainer {
    // 処理登録
    Just(1).eraseToAnyPublisher()
}

let reducerContainer2 = ReducerContainer {
    // 処理登録
    Deferred {
        // Defferredされている処理は即時実行されない
        Future { promise in
            promise(.success(2))
        }
    }
    .eraseToAnyPublisher()
}

let reducerContainer = ReducerContainer.combine([reducerContainer1, reducerContainer2])

reducerContainer.reducer().sink { value in
    print("receiveValue: \(value)")
}