how to prevent other views refreshing in state change swiftUI

Question

I have a bottom navigation view in my main View that I want to hide in some of the inner views by a @published variable that defined in ViewModel, but when I change the value of the variable all of the body refreshes in the main view and cause some problems(losing data). I want just to refresh the state of the bottom navigation, not the entire body. here is my code:

MainView

struct MainView: View {
@ObservedObject var viewModel = MainViewModel()


var body: some View {
    ZStack {
        VStack{
            content
        }
        
            VStack {
                Spacer()
                BottomNavigationView(mainViewModel: self.viewModel)
                        .padding(.horizontal)
            }.opacity(viewModel.isBottomNavigationVisible ? 1 : 0)


    }
}

var content: some View {
    switch self.viewModel.currentView {
    case .plan:
        return PlanMainView(mainViewModel: viewModel).eraseToAnyView()
    case .me:
        return MeMainView(mainViewModel: viewModel).eraseToAnyView()
    case .onBoarding:
        return OnBoardingHome(mainViewModel: viewModel).eraseToAnyView()
}}

MainViewModel

class MainViewModel: ObservableObject {
@Published private(set) var currentView: Modules = .main
@Published var isBottomNavigationVisible: Bool = true


func hideBottomBar() {
    self.isBottomNavigationVisible = false
}

func showBottomBar() {
    self.isBottomNavigationVisible = true
}

func GoToView(view: Modules) {
    self.currentView = view
}}

MeMainView

this is the view that I want to hide the bottom navigation in onAppear

struct MeMainView: View {
@ObservedObject var mainViewModel:MainViewModel


var body: some View {
    ZStack {
       Text("MewView")
    }.onAppear{
        self.mainViewModel.hideBottomBar()
    }
}}

Answer 1

Instead of computable property move content into separated view, as nothing changed for it so it will not be refreshed

    VStack{
        BodyView(viewModel: viewModel)
    }

and

struct BodyView: View {
   @ObservedObject var viewModel: MainViewModel

   var body: some View {
      switch self.viewModel.currentView {
      case .plan:
        return PlanMainView(mainViewModel: viewModel).eraseToAnyView()
      case .me:
        return MeMainView(mainViewModel: viewModel).eraseToAnyView()
      case .onBoarding:
        return OnBoardingHome(mainViewModel: viewModel).eraseToAnyView()
  }
}

Answer 2

var  myDict: [String: Double] = [:]

var body: some View {
      
                    HStack(alignment: .top) {
                        Button(action: {
                           self.myDict[self.tag] = amountValue

                        })
                  }

I have two user when I select 1st user and save some value to myDict, I want to add value for 2nd user to MyDict when i select 2nd user (means count of MyDict should be 2) but when i select 2nd user view is refreshing and value of 1st user is replace by 2nd user (means count of MyDict should be 1).

Is there any way so that i can have both the value in dict and not refresh?