Changing EnvironmentObject published property changes TabView - swiftui

Question

I have a an app I'm writing (first one) that has developed an issue. I have a tabbed view with multiple views, one of which is settings. On the settings view, various elements (mostly Toggles) bind to the global environment object appData. When I select something on the settings view, the TabView changes to the first tab away from the settings view.
The playground example below shows the issue. It does it the first time but not subsequent times. In my application, it does it every time. Not sure why it's different. To see the issue, load the playground code, click on settings and click the "Setting" toggle. It immediately jumps to MainView. The value for isSet in the application data does appear to get set.
I also see this on the emulator (set for iPhone SE) for my application.
I'm using XCode 13.4.
import SwiftUI
import Combine
import Foundation
import PlaygroundSupport
class ApplicationData: ObservableObject
{
#Published var isSet: Bool = false
}
struct MainView: View
{
var body: some View
{
Text("Main View")
}
}
struct SettingsView: View
{
#EnvironmentObject var appData : ApplicationData
var body: some View
{
Toggle("Setting", isOn: $appData.isSet)
}
}
struct TabbedView: View
{
#StateObject var appData = ApplicationData()
#State var selection: Int = 0
var body: some View
{
TabView(selection: $selection)
{
MainView().tabItem({Label("Main", systemImage: "menucard")})
SettingsView().tabItem({Label("Settings", systemImage: "gear")})
}
.environmentObject(appData)
}
}
let view = TabbedView()
let hostingVC = UIHostingController(rootView: view)
PlaygroundPage.current.liveView = hostingVC

Answer 1

I think the issue comes from TabView(selection:) itself. As you don't provide tags to identify the tabs, the view looses track when it is redrawn.
Either use TabView without selection:
TabView // here
{
MainView()
.tabItem({Label("Main", systemImage: "menucard")})
SettingsView()
.tabItem({Label("Settings", systemImage: "gear")})
}
Or – if with selection – you have to provide a .tag() so selection can track what is selected:
TabView(selection: $selection)
{
MainView()
.tabItem({Label("Main", systemImage: "menucard")})
.tag(0) // here
SettingsView()
.tabItem({Label("Settings", systemImage: "gear")})
.tag(1) // here
}