Dismiss a parent modal in SwiftUI from a NavigationView - ios

Question

I am aware of how to dismiss a modal from a child view using #Environment (\.presentationMode) var presentationMode / self.presentationMode.wrappedValue.dismiss() but this is a different issue.
When you present a multi-page NavigationView in a modal window, and have navigated through a couple of pages, the reference to presentationMode changes to be the NavigationView, so using self.presentationMode.wrappedValue.dismiss() simply pops the last NavigationView rather than dismissing the containing modal.
Is it possible - and if so how - to dismiss the containing modal from a page in a NavigationView tree?
Here's a simple example showing the problem. If you create an Xcode Single View app project using SwiftUI and replace the default ContentView code with this, it should work with no further changes.
import SwiftUI
struct ContentView: View {
#State var showModal: Bool = false
var body: some View {
Button(action: {
self.showModal.toggle()
}) {
Text("Launch Modal")
}
.sheet(isPresented: self.$showModal, onDismiss: {
self.showModal = false
}) {
PageOneContent()
}
}
}
struct PageOneContent: View {
var body: some View {
NavigationView {
VStack {
Text("I am Page One")
}
.navigationBarTitle("Page One")
.navigationBarItems(
trailing: NavigationLink(destination: PageTwoContent()) {
Text("Next")
})
}
}
}
struct PageTwoContent: View {
#Environment (\.presentationMode) var presentationMode
var body: some View {
NavigationView {
VStack {
Text("This should dismiss the modal. But it just pops the NavigationView")
.padding()
Button(action: {
// How to dismiss parent modal here instead
self.presentationMode.wrappedValue.dismiss()
}) {
Text("Finish")
}
.padding()
.foregroundColor(.white)
.background(Color.blue)
}
.navigationBarTitle("Page Two")
}
}
}

Answer 1

Here is possible approach based on usage own explicitly created environment key (actually I have feeling that it is not correct to use presentationMode for this use-case.. anyway).
Proposed approach is generic and works from any view in modal view hierarchy. Tested & works with Xcode 11.2 / iOS 13.2.
// define env key to store our modal mode values
struct ModalModeKey: EnvironmentKey {
static let defaultValue = Binding<Bool>.constant(false) // < required
}
// define modalMode value
extension EnvironmentValues {
var modalMode: Binding<Bool> {
get {
return self[ModalModeKey.self]
}
set {
self[ModalModeKey.self] = newValue
}
}
}
struct ParentModalTest: View {
#State var showModal: Bool = false
var body: some View {
Button(action: {
self.showModal.toggle()
}) {
Text("Launch Modal")
}
.sheet(isPresented: self.$showModal, onDismiss: {
}) {
PageOneContent()
.environment(\.modalMode, self.$showModal) // < bind modalMode
}
}
}
struct PageOneContent: View {
var body: some View {
NavigationView {
VStack {
Text("I am Page One")
}
.navigationBarTitle("Page One")
.navigationBarItems(
trailing: NavigationLink(destination: PageTwoContent()) {
Text("Next")
})
}
}
}
struct PageTwoContent: View {
#Environment (\.modalMode) var modalMode // << extract modalMode
var body: some View {
NavigationView {
VStack {
Text("This should dismiss the modal. But it just pops the NavigationView")
.padding()
Button(action: {
self.modalMode.wrappedValue = false // << close modal
}) {
Text("Finish")
}
.padding()
.foregroundColor(.white)
.background(Color.blue)
}
.navigationBarTitle("Page Two")
}
}
}

Answer 2

Another Approach would be to simply use a notification for this case and just reset the triggering flag for your modal.
It is not the most beautiful solution for me but it is the solution I am most likely to still understand in a few months.
import SwiftUI
struct ContentView: View {
#State var showModalNav: Bool = false
var body: some View {
Text("Present Modal")
.padding()
.onTapGesture {
showModalNav.toggle()
}.sheet(isPresented: $showModalNav, content: {
ModalNavView()
}).onReceive(NotificationCenter.default.publisher(for: Notification.Name(rawValue: "PushedViewNotifciation"))) { _ in
showModalNav = false
}
}
}
struct ModalNavView: View {
var body: some View {
NavigationView {
NavigationLink(
destination: PushedView(),
label: {
Text("Show Another View")
}
)
}
}
}
struct PushedView: View {
var body: some View {
Text("Pushed View").onTapGesture {
NotificationCenter.default.post(Notification.init(name: Notification.Name(rawValue: "PushedViewNotifciation")))
}
}
}
If you don't want to loosely couple the views through a notification you could also just use a binding for this like so:
struct ContentView: View {
#State var showModalNav: Bool = false
var body: some View {
Text("Present Modal")
.padding()
.onTapGesture {
showModalNav.toggle()
}.sheet(isPresented: $showModalNav, content: {
ModalNavView(parentShowModal: $showModalNav)
}).onReceive(NotificationCenter.default.publisher(for: Notification.Name(rawValue: "PushedViewNotifciation"))) { _ in
showModalNav = false
}
}
}
struct ModalNavView: View {
#Binding var parentShowModal: Bool
var body: some View {
NavigationView {
NavigationLink(
destination: PushedView(parentShowModal: $parentShowModal),
label: {
Text("Show Another View")
}
)
}
}
}
struct PushedView: View {
#Binding var parentShowModal: Bool
var body: some View {
Text("Pushed View").onTapGesture {
parentShowModal = false
}
}
}

Answer 3

If it's only two levels, and especially if you can dismiss the sheet at multiple levels, you could include showModal as a binding variable in your navigation views below, and then toggling it anywhere would dismiss the entire sheet.
I would assume you could do something similar with showModal as an EnvironmentObject as Wei mentioned above - which might be better if there are more than two levels and you only want to dismiss the sheet at the most specific level.
I can't remember if there's some reason to move away from doing this as a binding variable, but it seems to be working for me.
import SwiftUI
struct ContentView: View {
#State var showModal: Bool = false
var body: some View {
Button(action: {
self.showModal.toggle()
}) {
Text("Launch Modal")
}
.sheet(isPresented: self.$showModal, onDismiss: {
self.showModal = false
}) {
// Bind showModal to the corresponding property in PageOneContent
PageOneContent(showModal: $showModal)
}
}
}
Then you add showModal as a binding variable in PageOneContent, and it is bound to the state variable in ContentView.
struct PageOneContent: View {
// add a binding showModal var in here
#Binding var showModal: Bool
var body: some View {
NavigationView {
VStack {
Text("I am Page One")
}
.navigationBarTitle("Page One")
.navigationBarItems(
// bind showModal again to PageTwoContent
trailing: NavigationLink(destination: PageTwoContent(showModal: $showModal)) {
Text("Next")
})
}
}
}
Finally, in PageTwoContent, you can add showModal here (and in the NavigationLink in PageOneContent, you have bound PageTwoContent's showModal to PageOneContent). Then in your button, all you have to do is toggle it, and it will dismiss the sheet.
struct PageTwoContent: View {
// Add showModal as a binding var here too.
#Binding var showModal: Bool
var body: some View {
NavigationView {
VStack {
Text("This should dismiss the modal. But it just pops the NavigationView")
.padding()
Button(action: {
// This will set the showModal var back to false in all three views, and will dismiss the current sheet.
self.showModal.toggle()
}) {
Text("Finish")
}
.padding()
.foregroundColor(.white)
.background(Color.blue)
}
.navigationBarTitle("Page Two")
}
}
}

Answer 4

I found out you can actually make showModal into an EnvironmentObject, then simplify toggle the showModal to false on PageTwoContent to dismiss both PageOneContent and PageTwoContent.