SwiftUI-Flux.md

参考URL: SwiftUI-Flux

• CounterView.swift

import SwiftUI

struct CounterView : View {
    enum Action {
        case increment
        case decrement
    }
    
    @State var store = Store<Int, Action>(initial: 0) { count, action in
        switch action {
        case .increment:
            return count + 1
            
        case .decrement:
            return max(0, count - 1)
        }
    }
    
    var body: some View {
        VStack {
            Text("\(store.state)")
            
            HStack {
                Button(action: { self.store.dispatch(action: .decrement) }) {
                    Text("Decrement")
                }
                
                Button(action: { self.store.dispatch(action: .increment) }) {
                    Text("Increment")
                }
            }
        }
    }
}

#if DEBUG
struct CounterView_Previews : PreviewProvider {
    static var previews: some View {
        CounterView()
    }
}
#endif

• Store.swift

import SwiftUI
import Combine

final class Store<State, Action>: BindableObject {
    typealias Reducer = (State, Action) -> State
    
    let didChange = PassthroughSubject<State, Never>()
    
    var state: State {
        lock.lock()
        defer { lock.unlock() }
        return _state
    }
    
    private let lock = NSLock()
    private let reducer: Reducer
    private var _state: State
    
    init(initial state: State, reducer: @escaping Reducer) {
        _state = state
        self.reducer = reducer
    }
    
    func dispatch(action: Action) {
        lock.lock()
        
        let newState = reducer(_state, action)
        _state = newState
        
        lock.unlock()
        
        didChange.send(newState)
    }
}

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