WithViewStore not updating state and view, even if Store is updated

[drucelweisse]

Hello, recently I started adopting TCA and tried to refactor simple view from mvvm that fetches texts from file url. My problem is that WithViewStore doesn't update on Store changes. Maybe I miss something or do not understand?

Here's an example

public struct DetailInfo: ReducerProtocol {
    
    @Dependency(\.locale) var locale
    @Dependency(\.fileClient) var fileClient

    public struct State: Equatable {
        var texts: [String]

        public init(texts: [String] = []) {
            self.texts = texts
        }
        
        public static let initial = State()
    }

    public enum Action: Equatable {
        case fetch
        case loadedTexts([String])
    }

    public func reduce(into state: inout State, action: Action) -> EffectTask<Action> {
        switch action {
        case .fetch:
            return .task {
                let url = Resources.exampleURL
                let dict = try await fileClient.loadDecodable(type: [String: [String]].self, from: url)
                let texts = dict[locale.languageCode!]!
                return .loadedTexts(texts)
            }
        case let .loadedTexts(texts):
            state.texts = texts
            return .none
        }
    }
    
    public init() {
        
    }
}

View body

public var body: some View {
        WithViewStore(store) { viewStore in
            ScrollView(showsIndicators: false) {
                VStack(spacing: metrics.contentStackSpacing) {
                    image
                    VStack(alignment: .leading, spacing: metrics.headerToContentSpacing) {
                        header
                        content(texts: viewStore.texts)
                    }
                    .padding(.horizontal)
                    
                }
                .padding(.top, metrics.containerTopPadding)
                .padding(.bottom, metrics.containerBottomPadding)
            }
            .background(style.backgroundColor.ignoresSafeArea())
            .task {
                await viewStore.send(.fetch).finish()
            }
        }
}

And Logs:

WithViewStore< DetailInfo.State, DetailInfo.Action, _>@DetailInfo Feature/DetailInfoView.swift:31 (Initial state)
  DetailInfo.State(texts: [])
WithViewStore< DetailInfo.State, DetailInfo.Action, _>@DetailInfoFeature/DetailtInfoView.swift:31 (Initial state)
  DetailtInfo.State(texts: [])
received action:
  DetailInfo.Action.fetch
  (No state changes)
received action:
  DetailInfo.Action.loadedTexts(
    [
      [0]: "Text",
    ]
  )
- DetailInfo.State(texts: [])
+ DetailInfo.State(
+   texts: [
+     [0]: "Text",
+   ]
+ )

[lukeredpath]

How does this reducer fit in with the rest of your reducer structure and how are you creating the store that you pass into this view?

[tgrapperon]

@drucelweisse Did this fix your updating issue?

[drucelweisse]

I'm not sure about view recreation, Self._printChanges() didn't show anything, but holding a reference to Store fixed that problem

[mbrandonw]

@drucelweisse just to reiterate what @tgrapperon mentioned, you should aim to have a single Store at the root of your application, and "scopes" of the store should be passed down to child views by using the scope method on Store.

Further, the initializer WithViewStore(store) is discouraged due to the fact that it observes all state in the store. Instead, you should use the WithViewStore.init(_:observe:) initializer, which requires you to explicitly specify what state you want to observe.

You can also check out our dedicated article on performance to read more about why we recommend this.

[tgrapperon]

@drucelweisse Indeed, I assumed that you were partially converting a vanilla app to TCA, and that this Detail feature was the first entry point of TCA in your app, but if you're powering your whole app with TCA (which is the preferred approach), you should definitely scope stores as you drill down into your app's domains, as @mbrandonw said.

[drucelweisse]

Yeah, it's the first entry of TCA in the vanilla SwiftUI app, I'm going to make transition step by step. Thanks again! Can we close this discussion?