NavigationView always creates a new view - swiftui

Question

I created a NavigationView and it works, but everytime I click on a NavigationLink, SwiftUI recreates the destination view and resets every property in it. See this example:
struct NavView: View {
#State var selectionIndex: Int? = nil
let views = [
DestinationView(viewNumber: 1),
DestinationView(viewNumber: 2),
DestinationView(viewNumber: 3)
]
var body: some View {
NavigationView {
VStack {
NavigationLink(destination: self.views[0], tag: 0, selection: $selectionIndex) {
Text("View 1")
}
NavigationLink(destination: self.views[1], tag: 1, selection: $selectionIndex) {
Text("View 2")
}
NavigationLink(destination: self.views[2], tag: 0, selection: $selectionIndex) {
Text("View 3")
}
}
self.views[0]
}
}
}
struct DestinationView: View {
#State var viewNumber: Int
#State var count = 0
var body: some View {
VStack {
Text("View \(self.viewNumber)")
.font(.largeTitle)
Text("Count: \(self.count)")
Button(action: {
self.count += 1
}) {
Text("Increase counter")
}
}
}
}
In this example clicking for example on the View1 link opens the View 1. Pressing the button increases the count property. If you then click on the View2 button and then back the View1 button, the count property will be zero again.
EDIT
I also tried not to store the views and create them directly in body, as suggested in the comments. Doesn't work either :(
struct NavView: View {
#State var selectionIndex: Int? = nil
var body: some View {
NavigationView {
VStack {
NavigationLink(destination: DestinationView(viewNumber: 1), tag: 0, selection: $selectionIndex) {
Text("View 1")
}
NavigationLink(destination: DestinationView(viewNumber: 2), tag: 1, selection: $selectionIndex) {
Text("View 2")
}
NavigationLink(destination: DestinationView(viewNumber: 3), tag: 2, selection: $selectionIndex) {
Text("View 3")
}
}
}
}
}
EDIT 2
I also tried to store the views globally, I also tried with and without tag: and selection:

Answer 1

Issue in your code is that every time you are by default initializing count to 0 whenever we are navigating to DestinationView so trick is we have to update count value and save it some where in NavView.
First of all you have to create DestinationViewModel to keep track of your updated count values like below
class DestinationViewModel: ObservableObject {
#Published var viewNumber: Int
#Published var count: Int
init(_ viewNumber: Int, count: Int) {
self.viewNumber = viewNumber
self.count = count
}
}
Then you can access your DestinationViewModel in your DestinationView
struct DestinationView: View {
#EnvironmentObject var viewModel: DestinationViewModel
var body: some View {
VStack {
Text("View \(viewModel.viewNumber)")
.font(.largeTitle)
Text("Count: \(viewModel.count)")
Button(action: {
self.viewModel.count += 1
}) {
Text("Increase counter")
}
}
}
}
Below is your updated NavView
class DestinationViewModelContainer: ObservableObject {
#Published var viewModels: [DestinationViewModel]
init(_ viewModels: [DestinationViewModel]) {
self.viewModels = viewModels
}
}
struct NavView: View {
#EnvironmentObject var viewModelContainer: DestinationViewModelContainer
var body: some View {
NavigationView {
VStack {
NavigationLink(destination: DestinationView().environmentObject(viewModelContainer.viewModels[0])) {
Text("View 1")
}
NavigationLink(destination: DestinationView().environmentObject(viewModelContainer.viewModels[1])) {
Text("View 2")
}
NavigationLink(destination: DestinationView().environmentObject(viewModelContainer.viewModels[2])) {
Text("View 3")
}
}
}
}
}
and Here you can call your NavView from below code
let contentView = NavView().environmentObject(DestinationViewModelContainer([DestinationViewModel(1, count: 0), DestinationViewModel(2, count: 0),DestinationViewModel(3, count: 0)]))
Hope it will help you.