BaseStateExampleWithGenericAppState.swift

BaseStateExampleWithGenericAppState.swift

//How to use BaseState struct to share state between views in TCA architecture. 
// https://forums.swift.org/t/best-practice-for-sharing-data-between-many-features/37696/4

//This is a proof-of-concept only; it simply is an attempt to model how to get and set global shared state among different views in a TCA-style app.
import SwiftUI
import ComposableArchitecture

@dynamicMemberLookup

struct TCABaseState<State: Equatable>: Equatable{
    var sharedState: SharedState
    var state: State
    
    init(sharedState:  SharedState, state: State){
        self.sharedState = sharedState
        self.state = state
    }
    //https://www.swiftbysundell.com/tips/combining-dynamic-member-lookup-with-key-paths/
    subscript<T>(dynamicMember keyPath: WritableKeyPath<State, T>) -> T {
        get { state[keyPath: keyPath] }
        set { state[keyPath: keyPath] = newValue }
    }
    
}


struct SharedState: Equatable {
    var activeInternetConnection = true
    var isUserLoggedIn = false
}
struct TCAAppState: Equatable {
    
    var sharedState = SharedState()
    var person = Person()
    
    var personState: TCABaseState<Person> {get { TCABaseState(sharedState: sharedState, state: person)} set{self.person = newValue.state
        self.sharedState = newValue.sharedState
    }}
    
    var dog = Dog()
    var dogState: TCABaseState<Dog> {get { TCABaseState(sharedState: sharedState, state: dog)} set{self.dog = newValue.state
        self.sharedState = newValue.sharedState
    }}
    
}

struct Person: Equatable {
    var name = "Bill"
}

struct Dog: Equatable{
    var name = "Fido"
}

enum DogAction {
    case changeName
}

enum PersonAction {
    case changeName
    case toggleInternetState
}

enum TCAAppAction {
    case person(PersonAction)
    case dog(DogAction)
}

func displayInternetConnectionStatus(_ bool: Bool) -> some View {
    switch bool {
    case true: return Text("internet is connected")
    default: return Text("No internet")
    }
}

struct PersonView: View {
    let store: Store<TCABaseState<Person>, PersonAction>
    
    
    
    var body: some View {
        WithViewStore(store) {viewStore in
            Text("Hello \(viewStore.name)")
            Button("Change name"){viewStore.send(.changeName)}
            Button("ToggleInternetState"){viewStore.send(.toggleInternetState)}
            
            displayInternetConnectionStatus(viewStore.sharedState.activeInternetConnection)
        }
    }
}

struct DogView: View {
    let store: Store<TCABaseState<Dog>, DogAction>
    var body: some View {
        WithViewStore(store) {viewStore in
            Text("Hello \(viewStore.name)")
            displayInternetConnectionStatus(viewStore.sharedState.activeInternetConnection == true)
            
        }
    }
}


struct RootView: View {
    let store: Store<TCAAppState, TCAAppAction>
    
    var body: some View {
        PersonView(store: store.scope(state: {$0.personState}, action: {TCAAppAction.person($0)}))
            .padding()
        DogView(store: store.scope(state: {$0.dogState}, action: {TCAAppAction.dog($0)}))
            .padding()
    }
}

//struct ContentView_Previews: PreviewProvider {
//    static var previews: some View {
//        PersonView()
//    }
//}





var dogReducer = Reducer<TCABaseState<Dog>, DogAction, Void> {state, action, _ in
    switch action {
    case .changeName: state.state.name = "Rover"
        state.sharedState.activeInternetConnection = true
    }
    return .none}

var personReducer = Reducer<TCABaseState<Person>, PersonAction, Void> {state, action, _ in
    switch action {
    case .changeName: state.state.name = "Quinton"
        state.sharedState.activeInternetConnection = true
    case .toggleInternetState: state.sharedState.activeInternetConnection.toggle()
    }
    return .none}

var appReducer = Reducer.combine(dogReducer.pullback(state: \TCAAppState.dogState, action: /TCAAppAction.dog, environment: {}), personReducer.pullback(state: \TCAAppState.personState, action: /TCAAppAction.person, environment: {}))