What is different between #Binding and scroll down to dismiss presented view? - swiftui

Question

NavigationBarItem can't Click after dismiss view!
XCode11 beta3,
MacOS Catalina 10.15 Beta（19A501i）
When click DetailView button to dismiss by #Binding,
ContentView's navigationBarItem will disabled(Can't Click)!
But scroll down to dismiss will be fine(can click and will be print "Clicked!" in Debug Preview Mode)
struct DetailView: View {
#Binding var isPresented: Bool
var body: some View {
Group {
Text("Detail")
Button(action: {
self.isPresented.toggle()
}) {
Text("Dismiss")
}
}
}
}
struct ContentView : View {
#State var isPresented = false
var body: some View {
NavigationView{
Button(action: {self.isPresented.toggle()}){
Text("Show")
}
.presentation(!isPresented ? nil :
Modal(DetailView(isPresented: $isPresented)) {
print("dismissed")
}
)
.navigationBarTitle(Text("Test"))
.navigationBarItems(trailing:
Button(action: {print("Clicked!")} ) {
Image(systemName: "plus")
.frame(width: 44, height: 44)
.foregroundColor(.black)
.cornerRadius(22)
}
.padding(.trailing)
)
}
}
}

Answer 1

I'm inclined to think that there is a bug with modals. The onDismiss is never called when the modal goes away. However, I did found a workaround. Instead of dismissing by setting the isPresented variable from inside the modal view, I use the rootViewController from the main window, to call the UIKit dismiss method.
By dismissing the modal this way, the onDismiss closure is called properly, and it is there where I set isPresented = false, so the modal can be presented again.
The following code works, at least until a new version fixes the problem:
import SwiftUI
struct DetailView: View {
var body: some View {
Group {
Text("Detail")
Button(action: {
UIApplication.shared.windows[0].rootViewController?.dismiss(animated: true, completion: { })
}) {
Text("Dismiss")
}
}
}
}
struct ContentView : View {
#State var isPresented = false
var body: some View {
NavigationView{
Button(action: {self.isPresented.toggle()}){
Text("Show")
}
.presentation(!isPresented ? nil :
Modal(DetailView()) {
self.isPresented = false
print("dismissed")
}
)
.navigationBarTitle(Text("Test"))
.navigationBarItems(trailing:
Button(action: {print("Clicked!")} ) {
Image(systemName: "plus")
.frame(width: 44, height: 44)
.foregroundColor(.black)
.cornerRadius(22)
}
.padding(.trailing)
)
}
}
}