State variable not updated when changed in another View - swiftui

Question

I want to better understand binding data across view, so I made this demo app
First View - if isShowing is true, navigating to SecondView (binding value)
struct ParentView: View {
#State var isShowing = false
#State var value = 5
var body: some View {
NavigationView {
if value != 5 {
ThirdView(isShowing: $isShowing)
} else {
NavigationLink(isActive: $isShowing) {
SecondView(value: $value)
} label: {
Text("Go to second view")
}
}
}
}
}
Second view - updating ParentView value
struct SecondView: View {
#Binding var value: Int
#Environment(\.presentationMode) private var presentationMode
var body: some View {
VStack {
Button {
value = 5
presentationMode.wrappedValue.dismiss()
} label: {
Text("Return 5")
}
Button {
value = 1
presentationMode.wrappedValue.dismiss()
} label: {
Text("Return 1")
}
}
}
}
ThirdView - showing in FirstView in case value is not 5
struct ThirdView: View {
#Binding var isShowing: Bool
var body: some View {
ZStack {
Button {
isShowing.toggle()
} label: {
Text("Its a problem... Go to second view")
}
}
}
}
I tried to toggle isShowing in ThirdView so it can open SecondView to update value again.
But when button is clicked in ThirdView, it doesnt do anything.

Answer 1

The way you have things set up, it won't change. When value != 5, your `NavigationLink does not exist in the view. Instead, you want to trigger it programmatically like this:
struct ParentView: View {
#State var isShowing = false
#State var value = 5
var body: some View {
NavigationView {
VStack {
Text(value.description)
if value != 5 {
ThirdView(isShowing: $isShowing)
} else {
// Change out the NavigationLink for a button that sets isShowing.
Button {
isShowing = true
} label: {
Text("Go to second view")
}
}
}
// By placing it in the background, it is always available to be triggered.
.background(
NavigationLink(isActive: $isShowing) {
SecondView(value: $value)
} label: {
EmptyView()
}
)
}
}
}
Lastly, you don't need to toggle isShowing in ThirdView. You are better off either dismissing the view or setting the value to false. Otherwise, you can get confused what it is doing when you are in your various views.