ToolbarKeyboardViewBuilderProblem.swift

import SwiftUI

struct ContentView: View {
    @FocusState var isFocused: Bool
    @State var flag = true

    @State var a = ""
    @State var b = ""

    var body: some View {
        VStack {
            TextField("Enter a", text: $a)
                .focused($isFocused)
            TextField("Enter b", text: $b, prompt: Text("Enter b"))
            Text("isFocused: \(isFocused ? "Yes" : "No")")
            Toggle("Show Xxxx ", isOn: $flag)
        }
        .onAppear {
            // must delay changing isFocused, if not then no focus
            // is this a bug?
            DispatchQueue.main.asyncAfter(deadline: .now() + 0.1) {
                isFocused = true
            }
        }
        .toolbar {
            ToolbarItem(placement: .keyboard) {
                // @ViewBuilder ifView don't work: seems when isFocused change do not trigger update
                if isFocused {
                    Button("Focused") {}
                }
                // Behavior of this ifView is odd: if initial value is true, can turn off
                // but oddly, when turn off the above view then show even when isFocused is false!
                // if initial value is false, cannot turn on!
                if flag {
                    Button("Xxxx") {}
                }
            }
        }
    }
}

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