الحالة والإجراء والمختزل

ما هي The Composable Architecture؟

import ComposableArchitecture

// State holds data, Action describes events,
// a Reducer turns (state, action) into the next state.

ماكرو @Reducer

import ComposableArchitecture

@Reducer
struct CounterFeature {
    // State, Action, and body go here
}

تعريف الحالة

import ComposableArchitecture

@Reducer
struct CounterFeature {
    @ObservableState
    struct State: Equatable {
        var count = 0
    }
}

تعريف الإجراءات

import ComposableArchitecture

@Reducer
struct CounterFeature {
    @ObservableState
    struct State: Equatable { var count = 0 }

    enum Action {
        case incrementTapped
        case decrementTapped
    }
}

جسم Reducer

import ComposableArchitecture

@Reducer
struct CounterFeature {
    @ObservableState
    struct State: Equatable { var count = 0 }
    enum Action { case incrementTapped, decrementTapped }

    var body: some ReducerOf<Self> {
        Reduce { state, action in
            switch action {
            case .incrementTapped:
                state.count += 1
                return .none
            case .decrementTapped:
                state.count -= 1
                return .none
            }
        }
    }
}

إعادة التأثيرات

import ComposableArchitecture

// Every reducer branch returns an Effect.
// No side effect needed? Return .none.
// Need async work? Return an effect describing it.
Reduce { state, action in
    state.count += 1
    return .none
}

تتمركز تغييرات الحالة

import ComposableArchitecture

// Views send actions; the reducer mutates state.
// store.send(.incrementTapped)  ->  state.count += 1
// No direct state mutation outside the reducer.

نمذجة إدخال المستخدم في الحالة

import ComposableArchitecture

@Reducer
struct FormFeature {
    @ObservableState
    struct State: Equatable {
        var name = ""
        var isSubscribed = false
    }
    enum Action: BindableAction {
        case binding(BindingAction<State>)
    }
    var body: some ReducerOf<Self> {
        BindingReducer()
    }
}

إجراءات ذات قيم مرتبطة

import ComposableArchitecture

@Reducer
struct NumberFeature {
    @ObservableState
    struct State: Equatable { var value = 0 }
    enum Action {
        case reloadTapped
        case responseReceived(Int)
    }
    var body: some ReducerOf<Self> {
        Reduce { state, action in
            switch action {
            case .reloadTapped:
                return .none
            case let .responseReceived(value):
                state.value = value
                return .none
            }
        }
    }
}

لماذا تفيد Equatable مع الحالة

import ComposableArchitecture

@ObservableState
struct State: Equatable {
    var count = 0
    var title = ""
}
// Equatable enables change detection and test assertions.

بنية الميزة المكتملة

import ComposableArchitecture

@Reducer
struct CounterFeature {
    @ObservableState
    struct State: Equatable { var count = 0 }
    enum Action { case incrementTapped, decrementTapped }
    var body: some ReducerOf<Self> {
        Reduce { state, action in
            switch action {
            case .incrementTapped: state.count += 1; return .none
            case .decrementTapped: state.count -= 1; return .none
            }
        }
    }
}

فحص سريع: الأجزاء الثلاثة

خلاصة: State وAction وReducer

import ComposableArchitecture

// Recap: @Reducer + State + Action + body(Reduce)
// One type, one source of truth, predictable updates.