はじめに

@BindingStateの使い方を記録しておきます

完成

実装

Reducer

import Foundation
import ComposableArchitecture

public struct SampleReducer: Reducer {
    public init() {}

    // MARK: - State
    public struct State: Equatable {
+       @BindingState var text = "" // @BindingStateを付与
        
        public init() {}
    }

    // MARK: - Action
+   public enum Action: BindableAction, Equatable { // `BindableAction`に準拠させる
+       case binding(BindingAction<State>)
    }

    // MARK: - Reducer
    public var body: some ReducerOf<Self> {
+       BindingReducer() // ここが重要
        
        Reduce { state, action in
            switch action {
+           case .binding(\.$text):  // ここにtextの変更が流れてくる
+               print("変更:", state.text)
+               return .none
+           case .binding: // ここはその他の`binding`が流れてくる(今回はなし)
+               return .none
            }
        }
    }
}

View

import SwiftUI

struct ContentView: View {
    @ObservedObject private var viewStore: ViewStoreOf<SampleReducer>
    
    let store: StoreOf<SampleReducer>
    
    init(store: StoreOf<SampleReducer>) {
        self.store = store
        self.viewStore = ViewStore(store, observe: { $0 })
    }
    
    var body: some View {
        VStack {
            TextField("search", text: viewStore.$text) // 使う時は`$`を付ける
                .textFieldStyle(.roundedBorder)
        }
        .padding(.horizontal, 20)
    }
}

おわり

TCAめっちゃむずいです