SwiftUI: TabView and NavigationView play nicely on iPhone but not on iPad? - ios

Question

My app has a home screen showing a list of options and a few entirely different pages. Each leads to a dispatcher view with a tag indicating which page to show. I also want to be able to swipe between the pages. So I have this code (hugely simplified from the actual app, of course, but behaving in the same way):
struct Tab: Hashable {
let name: String
let id: Int
}
struct ContentView: View {
let tabs: [Tab] = [Tab(name: "first", id: 1), Tab(name: "second", id: 2), Tab(name: "third", id: 3)]
var body: some View {
NavigationView {
Form {
List (tabs, id: \.self) { tab in
NavigationLink(destination: Dispatcher(which: tab.id)) {
VStack (alignment: .leading) {
Text(tab.name).font(.headline).bold()
}
}
}
}.navigationTitle("test")
Text("hello")
}
}
}
struct Dispatcher: View {
var which: Int
#State private var tab = 2
var body: some View {
TabView(selection: $tab) {
Text("first page").tag(1)
Text("second page").tag(2)
Text("third page").tag(3)
}
.tabViewStyle(PageTabViewStyle(indexDisplayMode: .never))
.onAppear(perform: { tab = which })
}
}
On an iPhone, it works fine. But on an iPad, in either orientation, tapping any option in the home page takes me to the same sub-page, the one set by the initial value of the #State variable tab. The assignment in .onAppear is being executed, but the new value of tab is being ignored.
Any ideas gratefully received.
Jeremy

Answer 1

why not just do this:
struct Dispatcher: View {
#State var which: Int
var body: some View {
TabView(selection: $which) {
Text("first page").tag(1)
Text("second page").tag(2)
Text("third page").tag(3)
}
.tabViewStyle(PageTabViewStyle(indexDisplayMode: .never))
}
}

Answer 2

Now that workingdog has answered my question, can I perhaps expand it?
I implement his (or her, of course) solution on the iPad. I click on a selection in the NavigationView list (say, "second"). The clicked line highlights and the second page appears.
I then swipe to show another page (say "third"). That's fine.
But "second" remains highlighted in the NavigationView list, so I can't click on it to return to the second page.
Can I tell the NavigationView list to highlight the entry corresponding to the actual shown page? Or to highlight nothing?