I'm trying to have a very simple SwiftUI view hierarchy:
parent and a child.
The child should be able to dismiss itself with a tap of a button.
The following code works fine
struct ContentView: View {
var body: some View {
NavigationView {
NavigationLink {
ChildView()
} label: {
Text("Go")
}
}
}
}
struct ChildView: View {
#Environment(\.dismiss) var dismiss
var body: some View {
Text("Hello, world!")
.padding()
Button(action: {
dismiss()
}, label: {
Text("Dismiss")
})
}
}
However, when I try to add a simple state and init() to the ChildView, I'm hitting a compilation error
import SwiftUI
struct ContentView: View {
var body: some View {
NavigationView {
NavigationLink {
ChildView(foo: 42)
} label: {
Text("Go")
}
}
}
}
struct ChildView: View {
#Environment(\.dismiss) var dismiss
#State private var myInt: Int
init(foo: Int) {
self.myInt = foo // <--- ERROR IS HERE, "Variable 'self.myInt' used before being initialized"
}
var body: some View {
Text("Hello, world!")
.padding()
Button(action: {
dismiss()
}, label: {
Text("Dismiss")
})
}
}
This error is very puzzling. I tried different things and as far as I can tell, the problem is in the combination of init() and #Environment(\.dismiss) presents.
But I really need to have them both for the real project.
Anybody knows what's the reason for the error or how to fix it?
Xcode version: 13.4.1
A #State var has to be initialised differently:
self._myInt = State(initialValue: foo)
I started to use SwiftUI after a couple years of UIKit.. This is not a piece of cake lol.
Alright, so I am trying to build an app that has a tab bar with 2 elements. Each Tab with contain a ViewController (View now) and they will be embedded in a NavigationController (NavigationView now)
The actual result is this
and I am expecting to have a nav bar with a title set to Home.
Could you explain me what I do wrong here? i followed the documentation and a couple tutorials, and I don't seem to do differently.
import SwiftUI
struct TabBarView: View {
var body: some View {
TabView() {
RedView()
.tabItem({
Image(systemName: "house.fill")
Text("Home")
})
.tag(0)
BlueView()
.tabItem({
Image(systemName: "dollarsign.square.fill")
Text("Trade")
})
.tag(1)
}
}
}
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
TabBarView()
}
}
struct RedView: View {
var body: some View {
NavigationView {
List {
Text("test")
}
}
.navigationBarTitle("Home")
}
}
struct BlueView: View {
var body: some View {
NavigationView {
List {
Text("test2")
}
}
.navigationBarTitle("Trade")
}
}
This is the file that contains everything at the moment. Thanks in advance for any future help!
The .navigationBarTitle should be inside NavigationView
struct RedView: View {
var body: some View {
NavigationView {
List {
Text("test")
}
.navigationBarTitle("Home") // << here !!
}
}
}
I have lately been trying to make a tvOS app, but have run into the following rather annoying problem. I can't use navigation inside a TabView and still have the menu button on the remove take me back to the previous state.
struct TestView: View {
#State var selection : Int = 0
var body: some View {
TabView(selection: self.$selection) {
ExpView()
.tabItem {
HStack {
Image(systemName: "magnifyingglass")
Text("Explore")
}
}
.tag(0)
}
}
}
struct ExpView: View {
var body: some View {
NavigationView {
NavigationLink(destination: DetailView(title: "Hey")) {
Text("Detail")
}
}
}
}
struct DetailView: View {
var title : String
var body: some View {
VStack {
Text(title)
}
}
}
My question is: Is there any way to enable the menu button to go back to the previous view in the hierachy without dismissing the app completely?
You don't need to call dismiss on Menu it is called automatically for NavigationLink (so calling one more dismiss quits to main menu)
Here are fixed views. Tested with Xcode 11.4
struct ExploreView: View {
var body: some View {
NavigationView {
NavigationLink(destination: DetailView(title: "Hey")) {
Text("Detail")
}
}
}
}
struct DetailView: View {
var title : String
var body: some View {
VStack {
Text(title)
}
}
}
So I found a workaround for the issue.
If you place the navigationView outside the TabView and then use the following code it works:
struct TestView: View {
#State var selection : Int = 0
#State var hideNavigationBar : Bool
var body: some View {
NavigationView {
TabView(selection: self.$selection) {
ExpView(hideNavigationBar: self.$hideNavigationBar)
.tabItem {
HStack {
Image(systemName: "magnifyingglass")
Text("Explore")
}
}
.tag(0)
}
}
}
}
struct ExpView: View {
#Binding var hideNavigationBar : Bool
var body: some View {
NavigationLink(destination: DetailView(title: "Hey")) {
Text("Detail")
}.navigationBarTitle("")
.navigationBarHidden(self.hideNavigationBar)
.onAppear {
self.hideNavigationBar = true
}
}
}
struct DetailView: View {
var title : String
var body: some View {
VStack {
Text(title)
}
}
}
I want to show the user another view when the login is successful, otherwise stay on that view. I've done that with UIKit by performing a segue. Is there such an alternative in SwiftUI?
The NavigationButton solution does not work as I need to validate the user input before transitioning to the other view.
Button(action: {
let authService = AuthorizationService()
let result = authService.isAuthorized(username: self.username, password: self.password)
if(result == true) {
print("Login successful.")
// TODO: ADD LOGIC
*** HERE I WANT TO PERFORM THE SEGUE ***
presentation(MainView)
} else {
print("Login failed.")
}
}) {
Text("Login")
}
Xcode 11 beta 5.
NavigationDestinationLink and NavigationButton have been deprecated and replaced by NavigationLink.
Here's a full working example of programatically pushing a view to a NavigationView.
import SwiftUI
import Combine
enum MyAppPage {
case Menu
case SecondPage
}
final class MyAppEnvironmentData: ObservableObject {
#Published var currentPage : MyAppPage? = .Menu
}
struct NavigationTest: View {
var body: some View {
NavigationView {
PageOne()
}
}
}
struct PageOne: View {
#EnvironmentObject var env : MyAppEnvironmentData
var body: some View {
let navlink = NavigationLink(destination: PageTwo(),
tag: .SecondPage,
selection: $env.currentPage,
label: { EmptyView() })
return VStack {
Text("Page One").font(.largeTitle).padding()
navlink
.frame(width:0, height:0)
Button("Button") {
self.env.currentPage = .SecondPage
}
.padding()
.border(Color.primary)
}
}
}
struct PageTwo: View {
#EnvironmentObject var env : MyAppEnvironmentData
var body: some View {
VStack {
Text("Page Two").font(.largeTitle).padding()
Text("Go Back")
.padding()
.border(Color.primary)
.onTapGesture {
self.env.currentPage = .Menu
}
}.navigationBarBackButtonHidden(true)
}
}
#if DEBUG
struct NavigationTest_Previews: PreviewProvider {
static var previews: some View {
NavigationTest().environmentObject(MyAppEnvironmentData())
}
}
#endif
Note that the NavigationLink entity has to be present inside the View body.
If you have a button that triggers the link, you'll use the label of the NavigationLink.
In this case, the NavigationLink is hidden by setting its frame to 0,0, which is kind of a hack but I'm not aware of a better method at this point. .hidden() doesn't have the same effect.
You could do it like bellow, based on this response (it's packed like a Playground for easy testing:
import SwiftUI
import Combine
import PlaygroundSupport
struct ContentView: View {
var body: some View {
NavigationView {
MainView().navigationBarTitle(Text("Main View"))
}
}
}
struct MainView: View {
let afterLoginView = DynamicNavigationDestinationLink(id: \String.self) { message in
AfterLoginView(msg: message)
}
var body: some View {
Button(action: {
print("Do the login logic here")
self.afterLoginView.presentedData?.value = "Login successful"
}) {
Text("Login")
}
}
}
struct AfterLoginView: View {
let msg: String
var body: some View {
Text(msg)
}
}
PlaygroundPage.current.liveView = UIHostingController(rootView: ContentView())
Although this will work, I think that, from an architectural perspective, you try to push an "imperative programming" paradigm into SwiftUI's reactive logic.
I mean, I would rather implement it with the login logic wrapped into an ObjectBinding class with an exposed isLoggedin property and make the UI react to the current state (represented by isLoggedin).
Here's a very high level example :
struct MainView: View {
#ObjectBinding private var loginManager = LoginManager()
var body: some View {
if loginManager.isLoggedin {
Text("After login content")
} else {
Button(action: {
self.loginManager.login()
}) {
Text("Login")
}
}
}
}
I used a Bool state for my login transition, it seems pretty fluid.
struct ContentView: View {
#State var loggedIn = false
var body: some View {
VStack{
if self.loggedIn {
Text("LoggedIn")
Button(action: {
self.loggedIn = false
}) {
Text("Log out")
}
} else {
LoginPage(loggedIn: $loggedIn)
}
}
}
}
I was playing around with SwiftUI and want to be able to come back to the previous view when tapping a button, the same we use popViewController inside a UINavigationController.
Is there a provided way to do it so far ?
I've also tried to use NavigationDestinationLink to do so without success.
struct AView: View {
var body: some View {
NavigationView {
NavigationButton(destination: BView()) {
Text("Go to B")
}
}
}
}
struct BView: View {
var body: some View {
Button(action: {
// Trying to go back to the previous view
// previously: navigationController.popViewController(animated: true)
}) {
Text("Come back to A")
}
}
}
Modify your BView struct as follows. The button will perform just as popViewController did in UIKit.
struct BView: View {
#Environment(\.presentationMode) var mode: Binding<PresentationMode>
var body: some View {
Button(action: { self.mode.wrappedValue.dismiss() })
{ Text("Come back to A") }
}
}
Use #Environment(\.presentationMode) var presentationMode to go back previous view. Check below code for more understanding.
import SwiftUI
struct ContentView: View {
var body: some View {
NavigationView {
ZStack {
Color.gray.opacity(0.2)
NavigationLink(destination: NextView(), label: {Text("Go to Next View").font(.largeTitle)})
}.navigationBarTitle(Text("This is Navigation"), displayMode: .large)
.edgesIgnoringSafeArea(.bottom)
}
}
}
struct NextView: View {
#Environment(\.presentationMode) var presentationMode
var body: some View {
ZStack {
Color.gray.opacity(0.2)
}.navigationBarBackButtonHidden(true)
.navigationBarItems(leading: Button(action: {
self.presentationMode.wrappedValue.dismiss()
}, label: { Image(systemName: "arrow.left") }))
.navigationBarTitle("", displayMode: .inline)
}
}
struct NameRow: View {
var name: String
var body: some View {
HStack {
Image(systemName: "circle.fill").foregroundColor(Color.green)
Text(name)
}
}
}
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView()
}
}
With State Variables. Try that.
struct ContentViewRoot: View {
#State var pushed: Bool = false
var body: some View {
NavigationView{
VStack{
NavigationLink(destination:ContentViewFirst(pushed: self.$pushed), isActive: self.$pushed) { EmptyView() }
.navigationBarTitle("Root")
Button("push"){
self.pushed = true
}
}
}
.navigationViewStyle(StackNavigationViewStyle())
}
}
struct ContentViewFirst: View {
#Binding var pushed: Bool
#State var secondPushed: Bool = false
var body: some View {
VStack{
NavigationLink(destination: ContentViewSecond(pushed: self.$pushed, secondPushed: self.$secondPushed), isActive: self.$secondPushed) { EmptyView() }
.navigationBarTitle("1st")
Button("push"){
self.secondPushed = true;
}
}
}
}
struct ContentViewSecond: View {
#Binding var pushed: Bool
#Binding var secondPushed: Bool
var body: some View {
VStack{
Spacer()
Button("PopToRoot"){
self.pushed = false
} .navigationBarTitle("2st")
Spacer()
Button("Pop"){
self.secondPushed = false
} .navigationBarTitle("1st")
Spacer()
}
}
}
This seems to work for me on watchOS (haven't tried on iOS):
#Environment(\.presentationMode) var presentationMode
And then when you need to pop
self.presentationMode.wrappedValue.dismiss()
There is now a way to programmatically pop in a NavigationView, if you would like. This is in beta 5.
Notice that you don't need the back button. You could programmatically trigger the showSelf property in the DetailView any way you like. And you don't have to display the "Push" text in the master. That could be an EmptyView(), thereby creating an invisible segue.
(The new NavigationLink functionality takes over the deprecated NavigationDestinationLink)
import SwiftUI
struct ContentView: View {
var body: some View {
NavigationView {
MasterView()
}
}
}
struct MasterView: View {
#State var showDetail = false
var body: some View {
VStack {
NavigationLink(destination: DetailView(showSelf: $showDetail), isActive: $showDetail) {
Text("Push")
}
}
}
}
struct DetailView: View {
#Binding var showSelf: Bool
var body: some View {
Button(action: {
self.showSelf = false
}) {
Text("Pop")
}
}
}
#if DEBUG
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView()
}
}
#endif
It seems that a ton of basic navigation functionality is super buggy, which is disappointing and may be worth walking away from for now to save hours of frustration. For me, PresentationButton is the only one that works. TabbedView tabs don't work properly, and NavigationButton doesn't work for me at all. Sounds like YMMV if NavigationButton works for you.
I'm hoping that they fix it at the same time they fix autocomplete, which would give us much better insight as to what is available to us. In the meantime, I'm reluctantly coding around it and keeping notes for when fixes come out. It sucks to have to figure out if we're doing something wrong or if it just doesn't work, but that's beta for you!
Update: the NavigationDestinationLink API in this solution has been deprecated as of iOS 13 Beta 5. It is now recommended to use NavigationLink with an isActive binding.
I figured out a solution for programmatic pushing/popping of views in a NavigationView using NavigationDestinationLink.
Here's a simple example:
import Combine
import SwiftUI
struct DetailView: View {
var onDismiss: () -> Void
var body: some View {
Button(
"Here are details. Tap to go back.",
action: self.onDismiss
)
}
}
struct MainView: View {
var link: NavigationDestinationLink<DetailView>
var publisher: AnyPublisher<Void, Never>
init() {
let publisher = PassthroughSubject<Void, Never>()
self.link = NavigationDestinationLink(
DetailView(onDismiss: { publisher.send() }),
isDetail: false
)
self.publisher = publisher.eraseToAnyPublisher()
}
var body: some View {
VStack {
Button("I am root. Tap for more details.", action: {
self.link.presented?.value = true
})
}
.onReceive(publisher, perform: { _ in
self.link.presented?.value = false
})
}
}
struct RootView: View {
var body: some View {
NavigationView {
MainView()
}
}
}
I wrote about this in a blog post here.
You can also do it with .sheet
.navigationBarItems(trailing: Button(action: {
self.presentingEditView.toggle()
}) {
Image(systemName: "square.and.pencil")
}.sheet(isPresented: $presentingEditView) {
EditItemView()
})
In my case I use it from a right navigation bar item, then you have to create the view (EditItemView() in my case) that you are going to display in that modal view.
https://developer.apple.com/documentation/swiftui/view/sheet(ispresented:ondismiss:content:)
EDIT: This answer over here is better than mine, but both work: SwiftUI dismiss modal
What you really want (or should want) is a modal presentation, which several people have mentioned here. If you go that path, you definitely will need to be able to programmatically dismiss the modal, and Erica Sadun has a great example of how to do that here: https://ericasadun.com/2019/06/16/swiftui-modal-presentation/
Given the difference between declarative coding and imperative coding, the solution there may be non-obvious (toggling a bool to false to dismiss the modal, for example), but it makes sense if your model state is the source of truth, rather than the state of the UI itself.
Here's my quick take on Erica's example, using a binding passed into the TestModal so that it can dismiss itself without having to be a member of the ContentView itself (as Erica's is, for simplicity).
struct TestModal: View {
#State var isPresented: Binding<Bool>
var body: some View {
Button(action: { self.isPresented.value = false }, label: { Text("Done") })
}
}
struct ContentView : View {
#State var modalPresented = false
var body: some View {
NavigationView {
Text("Hello World")
.navigationBarTitle(Text("View"))
.navigationBarItems(trailing:
Button(action: { self.modalPresented = true }) { Text("Show Modal") })
}
.presentation(self.modalPresented ? Modal(TestModal(isPresented: $modalPresented)) {
self.modalPresented.toggle()
} : nil)
}
}
Below works for me in XCode11 GM
self.myPresentationMode.wrappedValue.dismiss()
instead of NavigationButton use Navigation DestinationLink
but You should import Combine
struct AView: View {
var link: NavigationDestinationLink<BView>
var publisher: AnyPublisher<Void, Never>
init() {
let publisher = PassthroughSubject<Void, Never>()
self.link = NavigationDestinationLink(
BView(onDismiss: { publisher.send() }),
isDetail: false
)
self.publisher = publisher.eraseToAnyPublisher()
}
var body: some View {
NavigationView {
Button(action:{
self.link.presented?.value = true
}) {
Text("Go to B")
}.onReceive(publisher, perform: { _ in
self.link.presented?.value = false
})
}
}
}
struct BView: View {
var onDismiss: () -> Void
var body: some View {
Button(action: self.onDismiss) {
Text("Come back to A")
}
}
}
In the destination pass the view you want to redirect, and inside block pass data you to pass in another view.
NavigationLink(destination: "Pass the particuter View") {
Text("Push")
}