SwiftUI - Why is TabView and its contents sometimes not refreshing when I change tabs on macOS?

Question

I'm trying to make a tabbed application on macOS with SwiftUI, and I have an odd issue with TabView.

When I have two tabs with TextFields each and save their text states to their respective private variables, something odd happens: When I switch from tab A to tab B after entering text into tab A's TextField, the tab indicator shows that I am still on tab A, but the content shows tab B's content. When I click on the button for tab B once again, it will still show tab B's content. Furthermore, when I press the button for tab A afterward, it will show the content of tab A, but the indicator for the tab still shows that I am on tab B.

What might I possibly be doing wrong?

Here is an example that illustrates my issue:

import SwiftUI

struct ContentView: View {
    var body: some View {
        TabView
            {
                TabAView()
                    .tabItem({Text("Tab A")})
                TabBView()
                    .tabItem({Text("Tab B")})
        }
    }
}

struct TabAView: View {
    @State private var text = ""
    var body: some View {
        VStack{
            Text("Tab A")
            TextField("Enter", text: $text)
        }
    }
}

struct TabBView : View {
    @State private var text = ""
    var body: some View {
        VStack {
            Text("Tab B")
            TextField("Enter", text: $text)
        }
    }
}

Here's a screen capture of the issue occurring:

Answer 1

This is definitely a bug in SwiftUI's implementation of TabView. But you can easily work around the problem by binding to TabView selection and setting the current tab manually like so:

struct ContentView: View {
    @State private var currentTab = 0
    var body: some View {
        TabView(selection: $currentTab)
            {
                TabAView()
                    .tabItem({Text("Tab A")})
                    .tag(0)
                    .onAppear() {
                        self.currentTab = 0
                    }
                TabBView()
                    .tabItem({Text("Tab B")})
                    .tag(1)
                    .onAppear() {
                        self.currentTab = 1
                    }
        }
    }
}

This bug only seems to manifest itself when the user changes tabs while a TextField has focus.

If you make the above changes to your code, it will work as expected.