Dismiss a View in SwiftUI when parent is re-rendered - swift

Question

Using iOS14.4, Swift5.3.2, XCode12.2,
I try to dismiss a SwiftUI's GridView (see below code).
The dismiss function is done by the \.presentationMode property of the #Environment as explained here.
Everything works until the moment where I introduced a #Binding property that mutates the parent-View at the very moment of the dismissal. (see dataStr = titles[idx] in code excerpt below).
I read that dismissal by \.presentationMode only works if the parent-View is not updated during the time the child-View is shown.
But I absolutely need to cause a mutation on the parent-View when the user taps on an element of the GridView at play here.
How can I re-write so that parent-View is updated AND dismissal of Child-View still work ?
struct GridView: View {
#Environment(\.presentationMode) private var presentationMode
#Binding var dataStr: String
#State private var titles = [String]()
let layout = [
GridItem(.flexible()),
GridItem(.flexible())
]
var body: some View {
ScrollView {
LazyVGrid(columns: layout, spacing: 10) {
ForEach(titles.indices, id: \.self) { idx in
VStack {
Text(titles[idx])
Image(titles[idx])
.resizable()
.aspectRatio(contentMode: .fit)
.frame(width: (UIScreen.main.bounds.width / 2) - 40)
}
.onTapGesture {
// WITHOUT THIS LINE OF CODE - EVERYTHING WORKS. WHY???????????????
dataStr = titles[idx]
self.presentationMode.wrappedValue.dismiss()
}
}
}
.padding()
}
}
}
As #jnpdx asked, here you can see the parent-View. Please find the GridView(dataStr: self.$dataStr) inside the .sheet() of the ToolBarItem()....
import SwiftUI
struct MainView: View {
#EnvironmentObject var mediaViewModel: MediaViewModel
#EnvironmentObject var commService: CommunicationService
#State private var dataStr = ""
#State private var connectionsLabel = ""
#State private var commumincationRole: THRole = .noMode
#State private var showingInfo = false
#State private var showingGrid = false
init() {
UINavigationBar.appearance().tintColor = UIColor(named: "title")
}
var body: some View {
NavigationView {
if mediaViewModel.mediaList.isEmpty {
LoadingAnimationView()
.navigationBarHidden(true)
.ignoresSafeArea()
} else {
if dataStr.isEmpty {
MainButtonView(dataStr: $dataStr,
commumincationRole: $commumincationRole,
connectionsLabel: $connectionsLabel
)
.navigationBarHidden(false)
.navigationTitle("Trihow Pocket")
.navigationBarColor(backgroundColor: UIColor(named: "btnInactive"), titleColor: UIColor(named: "title"))
.toolbar {
ToolbarItem(placement: .navigationBarLeading) {
Button(action: {
showingInfo.toggle()
}) {
Image(systemName: "ellipsis")
}
.sheet(isPresented: $showingInfo) {
InfoView()
}
}
ToolbarItem(placement: .navigationBarTrailing) {
Button(action: {
showingGrid.toggle()
}) {
Image(systemName: "square.grid.3x3")
}
.sheet(isPresented: $showingGrid) {
// GRIDVIEW CALLING THE CHILD-VIEW IS HERE !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
GridView(dataStr: self.$dataStr)
}
}
}
} else {
let str = self.dataStr
#if os(iOS)
PageViewiOS(dataStr: self.$dataStr, commumincationRole: $commumincationRole)
.navigationBarHidden(true)
.onAppear() {
if commumincationRole == .moderatorMode {
commService.send(thCmd: THCmd(key: .tagID, sender: "", content: str))
}
}
.ignoresSafeArea()
#elseif os(macOS)
PageViewMacOS()
.ignoresSafeArea()
#endif
}
}
}
.onTHComm_PeerAction(service: commService) { (peers) in
let idsOrNames = peers.map { (peer) -> String in
if let id = peer.id {
return "\(id)"
} else if let name = peer.name {
return "\(name)"
} else {
return ""
}
}
connectionsLabel = "Connected devices: \n\(idsOrNames.lineFeedString)"
}
.onTHComm_ReceiveCmd(service: commService) { (thCmd) in
if (commumincationRole == .moderatorMode) || (commumincationRole == .discoveryMode) {
switch thCmd.key {
case .tagID:
dataStr = thCmd.content
case .closeID:
dataStr = ""
default:
break
}
}
}
.onTHComm_LastMessageLog(service: commService) { (log) in
print(log)
}
.navigationViewStyle(StackNavigationViewStyle())
}
}
struct MainView_Previews: PreviewProvider {
static var previews: some View {
MainView()
.environmentObject(MediaViewModel())
.environmentObject(MultipeerConnectivityService())
}
}

Answer 1

With the help of #jnpdx, I found a workaround.
Wrap the binding-property (i.e. dataStr in my example) into a delayed block that executes after something like 50ms:
.onTapGesture {
DispatchQueue.main.asyncAfter(deadline: .now() + .milliseconds(50)) {
dataStr = thumNames[idx]
}
self.presentationMode.wrappedValue.dismiss()
}
Of course, this workaround only works in my case, because I do no longer need to keep the Child-View open. There might be other situations where the Parent-View needs to be updated prior to closing the Child-View (i.e. here the update of dataStr can be done right at the closing moment of the Child-View).
I am still wondering how to deal with dismiss-problems for any case where the Child-View makes the Parent-View update prior to closing. These are situations where SwiftUI's dismiss function no longer work from then on. Any mutation of the Parent-View cause the Child-View to separate somehow and dismisss no longer works.
Any idea what to do in that case ?