Non-deprecated way to call NavigationLink on Buttons - swiftui

This is the old way of calling NavigationLink on Buttons
struct ContentView: View {
#State private var selection: String? = nil
var body: some View {
NavigationView {
VStack {
NavigationLink(destination: View1(), tag: "tag1", selection: $selection) {
EmptyView()
}
NavigationLink(destination: NotView1(), tag: "tag2", selection: $selection) {
EmptyView()
}
Button("Do work then go to View1") {
// do some work that takes about 1 second
mySleepFunctionToSleepOneSecond()
selection = "tag1"
}
Button("Instantly go to NotView1") {
selection = "tag2"
}
}
.navigationTitle("Navigation")
}
}
}
This code works perfectly. It can go to different View targets depending on which button is clicked. Not only that, it guarantees all work is done BEFORE navigating to the target view. However, the only issue is that 'init(destination:tag:selection:label:)' was deprecated in iOS 16.0: use NavigationLink(value:label:) inside a List within a NavigationStack or NavigationSplitView
I get NavigationStack is awesome and such. But how can I translate the code to use the new NavigationStack + NavigationLink. Especially, how can I make sure work is done Before navigation?

Using new NavigationStack and its path property you can do much more. Your example will be transformed to
struct ContentView: View {
#State private var path = [String]()
var body: some View {
NavigationStack(path: $path) {
VStack {
Button("Do work then go to View1") {
// do some work that takes about 1 second
mySleepFunctionToSleepOneSecond()
path.append("tag1")
}
Button("Instantly go to NotView1") {
path.append("tag2")
}
}
.navigationTitle("Navigation")
.navigationDestination(for: String.self) { route in
switch route {
case "tag1":
EmptyView()
case "tag2":
EmptyView()
default:
EmptyView()
}
}
}
}
}
Check this video. There you can find more use cases.

For using non deprecated and after doing some work if we want to go to next view or in anyview there is something called ".navigationDestination". Let's see that using simple example.
#State var bool : Bool = false
var body: some View {
NavigationStack {
VStack {
Text("Hello, world!")
Button {
//Code here before changing the bool value
bool = true
} label: {
Text("Navigate Button")
}
}.navigationDestination(isPresented: $bool) {
SwiftUIView()
}
}
}
In this code we change take bool value as false and change it to true when our work is done using button.
.navigationDestination(isPresented: Binding<Bool>, destination: () -> View)
In .navigationDestination pass the Binding bool and provide the view you want to navigate.
You can use .navigationDestination multiple times.
Hope you found this useful.

Related

NavigationStack not affected by EnvironmentObject changes

I'm attempting to use #EnvironmentObject to pass an #Published navigation path into a SwiftUI NavigationStack using a simple wrapper ObservableObject, and the code builds without issue, but working with the #EnvironmentObject has no effect. Here's a simplified example that still exhibits the issue:
import SwiftUI
class NavigationCoordinator: ObservableObject {
#Published var path = NavigationPath()
func popToRoot() {
path.removeLast(path.count)
}
}
struct ContentView: View {
#StateObject var navigationCoordinator = NavigationCoordinator()
var body: some View {
NavigationStack(path: $navigationCoordinator.path, root: {
FirstView()
})
.environmentObject(navigationCoordinator)
}
}
struct FirstView: View {
var body: some View {
VStack {
NavigationLink(destination: SecondView()) {
Text("Go To SecondView")
}
}
.navigationTitle(Text("FirstView"))
}
}
struct SecondView: View {
var body: some View {
VStack {
NavigationLink(destination: ThirdView()) {
Text("Go To ThirdView")
}
}
.navigationTitle(Text("SecondView"))
}
}
struct ThirdView: View {
#EnvironmentObject var navigationCoordinator: NavigationCoordinator
var body: some View {
VStack {
Button("Pop to FirstView") {
navigationCoordinator.popToRoot()
}
}
.navigationTitle(Text("ThirdView"))
}
}
I am:
Passing the path into the NavigationStack path parameter
Sending the simple ObservableObject instance into the NavigationStack via the .environmentObject() modifier
Pushing a few simple child views onto the stack
Attempting to use the environment object in ThirdView
NOT crashing when attempting to use the environment object (e.g. "No ObservableObject of type NavigationCoordinator found")
Am I missing anything else that would prevent the deeply stacked view from using the EnvironmentObject to affect the NavigationStack's path? It seems like the NavigationStack just isn't respecting the bound path.
(iOS 16.0, Xcode 14.0)
The reason your code is not working is that you haven't added anything to your path, so your path is empty. You can simply verify this by adding print(path.count) in your popToRoot method it will print 0 in the console.
To work with NavigationPath you need to use navigationDestination(for:destination:) ViewModifier, So for your example, you can try something like this.
ContentView:- Change NavigationStack like this.
NavigationStack(path: $navigationCoordinator.path) {
VStack {
NavigationLink(value: 1) {
Text("Go To SecondView")
}
}
.navigationDestination(for: Int.self) { i in
if i == 1 {
SecondView()
}
else {
ThirdView()
}
}
}
SecondView:- Change NavigationLink like this.
NavigationLink(value: 2) {
Text("Go To ThirdView")
}
This workaround works with Int but is not a better approach, so my suggestion is to use a custom Array as a path. Like this.
enum AppView {
case second, third
}
class NavigationCoordinator: ObservableObject {
#Published var path = [AppView]()
}
NavigationStack(path: $navigationCoordinator.path) {
FirstView()
.navigationDestination(for: AppView.self) { path in
switch path {
case .second: SecondView()
case .third: ThirdView()
}
}
}
Now change NavigationLink in FirstView and SecondView like this.
NavigationLink(value: AppView.second) {
Text("Go To SecondView")
}
NavigationLink(value: AppView.third) {
Text("Go To ThirdView")
}
The benefit of the above is now you can use the button as well to push a new screen and just need to append in your path.
path.append(.second)
//OR
path.append(.third)
This will push a respected view.
For more details, you can read the Apple document of NavigationLink and NavigationPath.

SwiftUI - TabView/NavigationLink navigation breaks when using a custom binding

I'm having trouble with what I think may be a bug, but most likely me doing something wrong.
I have a slightly complex navigation state variable in my model that I'm using for tracking/setting state between tab and sidebar presentations when multitasking on iPad. That all works fine except in tab mode, once I use a navigation link once I can't seem to use one again, whether the binding is on my tab view or navigation links in a list.
Would really appreciate any thoughts on this,
Cheers!
Example
NavigationItem.swift
enum SubNavigationItem: Hashable {
case overview, user, hobby
}
enum NavigationItem: Hashable {
case home(SubNavigationItem)
case settings
}
Model.swift
final class Model: ObservableObject {
#Published var selectedTab: NavigationItem = .home(.overview)
}
SwiftUIApp.swift
#main
struct SwiftUIApp: App {
#StateObject var model = Model()
var body: some Scene {
WindowGroup {
ContentView()
.environmentObject(model)
}
}
}
ContentView.swift
struct ContentView: View {
var body: some View {
AppTabNavigation()
}
}
AppTabNavigation.swift
struct AppTabNavigation: View {
#EnvironmentObject private var model: Model
var body: some View {
TabView(selection: $model.selectedTab) {
NavigationView {
HomeView()
}
.tabItem {
Label("Home", systemImage: "house")
}
.tag(NavigationItem.home(.overview))
NavigationView {
Text("Settings View")
}
.tabItem {
Label("Settings", systemImage: "gear")
}
.tag(NavigationItem.settings)
}
}
}
HomeView.swift
I created a binding here because selection required an optional <NavigationItem?> not
struct HomeView: View {
#EnvironmentObject private var model: Model
var body: some View {
let binding = Binding<NavigationItem?>(
get: {
model.selectedTab
},
set: {
guard let item = $0 else { return }
model.selectedTab = item
}
)
List {
NavigationLink(
destination: Text("Users"),
tag: .home(.user),
selection: binding
) {
Text("Users")
}
NavigationLink(
destination: Text("Hobbies"),
tag: .home(.hobby),
selection: binding
) {
Text("Hobbies")
}
}
.navigationTitle("Home")
}
}
Second Attempt
I tried making the selectedTab property optional as #Lorem Ipsum suggested. Which means I can remove the binding there. But then the TabView doesn't work with the property. So I create a binding for that and have the same issue but with the tab bar!
Make the selected tab optional
#Published var selectedTab: NavigationItem? = .home(.overview)
And get rid of that makeshift binding variable. Just use the variable
$model.selectedTab
If the variable can never be nil then something is always selected IAW with that makeshift variable it will just keep the last value.

How can I use multiple fullScreenCover in IOS14

I want to present the two destinations view in full screen mode from a single view.
Below is a sample of my code. Seem that the function only works for single presentation, if I have a second fullScreenCover defined, the first fullScreenCover didn't work properly.Is that any workaround at this moment?
import SwiftUI
struct TesFullScreen: View {
init(game : Int){
print(game)
}
var body: some View {
Text("Full Screen")
}
}
ContentView
import SwiftUI
struct ContentView: View {
#State var showFullScreen1 : Bool = false
#State var showFullScreen2 : Bool = false
var body: some View {
NavigationView {
VStack {
Spacer()
Button(action: { self.showFullScreen1 = true }) {
Text("Show Full Screen 1")
}
Button(action: { self.showFullScreen2 = true }) {
Text("Show Full Screen 2")
}
Spacer()
}
.navigationBarTitle("TextBugs", displayMode: .inline)
}
.fullScreenCover(isPresented: self.$showFullScreen1){
TesFullScreen(game: 1)
}
.fullScreenCover(isPresented: self.$showFullScreen2){
TesFullScreen(game: 2)
}
}
}
Not always the accepted answer works (for example if you have a ScrollView with subviews (cells in former days) which holds the buttons, that set the navigational flags).
But I found out, that you also can add the fullScreen-modifier onto an EmptyView. This code worked for me:
// IMPORTANT: Has to be within a container (e.g. VStack, HStack, ZStack, ...)
if myNavigation.flag1 || myNavigation.flag2 {
EmptyView().fullScreenCover(isPresented: $myNavigation.flag1)
{ MailComposer() }
EmptyView().fullScreenCover(isPresented: $myNavigation.flag2)
{ RatingStore() }
}
Usually some same modifier added one after another is ignored. So the simplest fix is to attach them to different views, like
struct FullSContentView: View {
#State var showFullScreen1 : Bool = false
#State var showFullScreen2 : Bool = false
var body: some View {
NavigationView {
VStack {
Spacer()
Button(action: { self.showFullScreen1 = true }) {
Text("Show Full Screen 1")
}
.fullScreenCover(isPresented: self.$showFullScreen1){
Text("TesFullScreen(game: 1)")
}
Button(action: { self.showFullScreen2 = true }) {
Text("Show Full Screen 2")
}
.fullScreenCover(isPresented: self.$showFullScreen2){
Text("TesFullScreen(game: 2)")
}
Spacer()
}
.navigationBarTitle("TextBugs", displayMode: .inline)
}
}
}
Alternate is to have one .fullScreenCover(item:... modifier and show inside different views depending on input item.
The only thing that worked for me was the answer in this link:
https://forums.swift.org/t/multiple-sheet-view-modifiers-on-the-same-view/35267
Using the EmptyView method or other solutions always broke a transition animation on one of the two presentations. Either transitioning to or from that view and depending on what order I chose them.
Using the approach by Lantua in the link which is using the item argument instead of isPresented worked in all cases:
enum SheetChoice: Hashable, Identifiable {
case a, b
var id: SheetChoice { self }
}
struct ContentView: View {
#State var sheetState: SheetChoice?
var body: some View {
VStack {
...
}
.sheet(item: $sheetState) { item in
if item == .a {
Text("A")
} else {
Text("B")
}
}
}
}
The sheetState needs to be optional for it to work.

Corrupted Navigation Views

I'm pretty sure this is a bug in SwiftUI, but I wondered if anyone has encountered it and figured out a workaround. My normal use case is to have a search field appear, but I've simplified it to the point where a simple text string exhibits the bug.
Create a single-view app, copy this into ContentView, and run it. Tap the search icon twice, then scroll the view; you'll see the text scrolling UNDER the title.
import SwiftUI
struct ContentView: View {
private var items = (0 ... 50).map {String($0)}
#State private var condition = false
var searchButton: some View {
Button(action: {self.condition.toggle()}) {
Image(systemName: "magnifyingglass").imageScale(.large)
}
}
var body: some View {
NavigationView {
VStack {
if condition {
Text("Peekaboo")
}
List {
ForEach(items, id: \.self) {item in
HStack {
Text(item)
}
}
}
}
.navigationBarTitle("List of Items")
.navigationBarItems(leading: searchButton)
}
}
}
Maybe it is a bug, submit feedback to Apple, but currently this is how NavigationView behaves - it collapses navigation bar only if its top content is List/ScrollView/Form. So to solve the issue move your VStack either into a List or out of NavigationView
1)
var body: some View {
NavigationView {
List {
if condition {
Text("Peekaboo")
}
ForEach(items, id: \.self) {item in
2)
var body: some View {
VStack {
if condition {
Text("Peekaboo")
}
NavigationView {
List {
It seems that a View cannot cope with variable number of views.
A workaround this strange behavior is this:
import SwiftUI
struct ContentView: View {
private var items = (0 ... 50).map {String($0)}
#State private var condition = false
var searchButton: some View {
Button(action: {self.condition.toggle()}) {
Image(systemName: "magnifyingglass").imageScale(.large)
}
}
var body: some View {
NavigationView {
VStack {
if condition {
Text("Peekaboo")
} else {
Text("")
}
// or use this Text(condition ? "Peekaboo" : "")
List {
ForEach(items, id: \.self) {item in
HStack {
Text(item)
}
}
}
}
.navigationBarTitle("List of Items")
.navigationBarItems(leading: searchButton)
}
}
}
Let me know if it works, if not let us know what device/system you are using. Tested with Xcode 11.6 beta, Mac 10.15.5, target ios 13.5 and mac catalyst.

Is it possible for a NavigationLink to perform an action in addition to navigating to another view?

I'm trying to create a button that not only navigates to another view, but also run a function at the same time. I tried embedding both a NavigationLink and a Button into a Stack, but I'm only able to click on the Button.
ZStack {
NavigationLink(destination: TradeView(trade: trade)) {
TradeButton()
}
Button(action: {
print("Hello world!") //this is the only thing that runs
}) {
TradeButton()
}
}
You can use .simultaneousGesture to do that. The NavigationLink will navigate and at the same time perform an action exactly like you want:
NavigationLink(destination: TradeView(trade: trade)) {
Text("Trade View Link")
}.simultaneousGesture(TapGesture().onEnded{
print("Hello world!")
})
You can use NavigationLink(destination:isActive:label:). Use the setter on the binding to know when the link is tapped. I've noticed that the NavigationLink could be tapped outside of the content area, and this approach captures those taps as well.
struct Sidebar: View {
#State var isTapped = false
var body: some View {
NavigationLink(destination: ViewToPresent(),
isActive: Binding<Bool>(get: { isTapped },
set: { isTapped = $0; print("Tapped") }),
label: { Text("Link") })
}
}
struct ViewToPresent: View {
var body: some View {
print("View Presented")
return Text("View Presented")
}
}
The only thing I notice is that setter fires three times, one of which is after it's presented. Here's the output:
Tapped
Tapped
View Presented
Tapped
NavigationLink + isActive + onChange(of:)
// part 1
#State private var isPushed = false
// part 2
NavigationLink(destination: EmptyView(), isActive: $isPushed, label: {
Text("")
})
// part 3
.onChange(of: isPushed) { (newValue) in
if newValue {
// do what you want
}
}
This works for me atm:
#State private var isActive = false
NavigationLink(destination: MyView(), isActive: $isActive) {
Button {
// run your code
// then set
isActive = true
} label: {
Text("My Link")
}
}
Use NavigationLink(_:destination:tag:selection:) initializer and pass your model's property as a selection parameter. Because it is a two-way binding, you can define didset observer for this property, and call your function there.
struct ContentView: View {
#EnvironmentObject var navigationModel: NavigationModel
var body: some View {
NavigationView {
List(0 ..< 10, id: \.self) { row in
NavigationLink(destination: DetailView(id: row),
tag: row,
selection: self.$navigationModel.linkSelection) {
Text("Link \(row)")
}
}
}
}
}
struct DetailView: View {
var id: Int;
var body: some View {
Text("DetailView\(id)")
}
}
class NavigationModel: ObservableObject {
#Published var linkSelection: Int? = nil {
didSet {
if let linkSelection = linkSelection {
// action
print("selected: \(String(describing: linkSelection))")
}
}
}
}
It this example you need to pass in your model to ContentView as an environment object:
ContentView().environmentObject(NavigationModel())
in the SceneDelegate and SwiftUI Previews.
The model conforms to ObservableObject protocol and the property must have a #Published attribute.
(it works within a List)
I also just used:
NavigationLink(destination: View()....) {
Text("Demo")
}.task { do your stuff here }
iOS 15.3 deployment target.