I am creating a SwiftUI app with a wizard-like navigation. I have already build a WizardView, in which I then embed the single pages. The WizardView should take care of general stuff like displaying everything in a nice looking frame, display navigation buttons, and so on. Basically everything seems to look right, so I started to have a look at how navigation works in SwiftUI.
This is a condensed version of what I ended up with. The problem is, I can't find a possible solution for passing the nextView from the concrete page to the WizardView struct.
import SwiftUI
struct WizardView<Content: View>: View {
private let content: () -> Content
private var canNavigateBack: Bool
private var canNavigateForth: Bool
// TODO
// How do I pass this as parameter, which has to be optional or some default view,
// as the last screen won't have a next one.
private var nextView = EmptyView()
init(canNavigateBack: Bool? = true,
canNavigateForth: Bool? = true,
#ViewBuilder content: #escaping () -> Content) {
self.canNavigateBack = canNavigateBack!;
self.canNavigateForth = canNavigateForth!;
self.content = content
}
var body: some View {
VStack(spacing: 15) {
content()
HStack {
// TODO Implement correct back button
if (canNavigateBack) {
NavigationLink(destination: EmptyView()) {
Text("Back")
}
}
if (canNavigateBack && canNavigateForth) {
Spacer()
}
// Naviate to next screen
if (canNavigateForth) {
NavigationLink(destination: nextView) {
Text("Next")
}
}
}
}
.padding()
}
}
struct DemoView_Previews: PreviewProvider {
static var previews: some View {
VStack {
/**
* The usage within the different screens should be something like this
*/
Divider()
WizardView(canNavigateBack: false) {
Text("This would be the first screen, without back navigation.")
}
Divider()
WizardView() {
Text("This would be another screen.")
}
Divider()
WizardView(canNavigateForth: false) {
Text("This is the last screen, without next button.")
}
Divider()
}
}
}
I am fairly new to Swift and SwiftUI so maybe I just don't understand some basic concepts here.
Update:
Here I found something, that helped me, at least a little. SwiftUI MVVM Coordinator/Router/NavigationLink
I will update this, question as soon, as I made my way through.
Related
I have a simple View showing a list of 3 items. When the user taps on an item, it navigates to the next view. This works fine. However, I would like to also perform an action (set a variable in a View Model) when a list item is tapped.
Is this possible? Here's the code:
import SwiftUI
struct SportSelectionView: View {
#EnvironmentObject var workoutSession: WorkoutManager
let sports = ["Swim", "Bike", "Run"]
var body: some View {
List(sports, id: \.self) { sport in
NavigationLink(destination: ContentView().environmentObject(workoutSession)) {
Text(sport)
}
}.onAppear() {
// Request HealthKit store authorization.
self.workoutSession.requestAuthorization()
}
}
}
struct DisciplineSelectionView_Previews: PreviewProvider {
static var previews: some View {
SportSelectionView().environmentObject(WorkoutManager())
}
}
The easiest way I've found to get around this issue is to add an .onAppear call to the destination view of the NavigationLink. Technically, the action will happen when the ContentView() appears and not when the NavigationLink is clicked.. but the difference will be milliseconds and probably irrelevant.
NavigationLink(destination:
ContentView()
.environmentObject(workoutSession)
.onAppear {
// add action here
}
)
Here's a solution that is a little different than the onAppear approach. By creating your own Binding for isActive in the NavigationLink, you can introduce a side effect when it's set. I've implemented it here all within the view, but I would probably do this in an ObservableObject if I were really putting it into practice:
struct ContentView: View {
#State var _navLinkActive = false
var navLinkBinding : Binding<Bool> {
Binding<Bool> { () -> Bool in
return _navLinkActive
} set: { (newValue) in
if newValue {
print("Side effect")
}
_navLinkActive = newValue
}
}
var body: some View {
NavigationView {
NavigationLink(
destination: Text("Dest"),
isActive: navLinkBinding,
label: {
Text("Navigate")
})
}
.navigationViewStyle(StackNavigationViewStyle())
}
}
I am trying to create a simple master/detail app in Xcode.
I want that the detail view is
struct EditingView: View
{
var body: some View {
var mainVertical: VStack = VStack() //error here
{
var previewArea: HStack = HStack()
{
var editorButton: Button = Button()
//the same with return editorButton
// I have to add other controls, like a WKWebView
}
return previewArea
//this is a simple version, layout will have other stacks with controls inside
}
return mainVertical
}
}
but I get
Generic parameter 'Content' could not be inferred
The IDE offers me to fix but if I do that, it writes a generic type I have to fill but then other errors come, f.i. if I put AnyView o TupleView.
I would like that it infers everything, what is wrong that it cannot understand?
In SwiftUI you usually don't need to reference your controls. You can apply modifiers to them directly in the view.
This is the preferred way:
struct ContentView: View {
var body: some View {
VStack {
HStack {
Button("Click me") {
// some action
}
}
}
.background(Color.red) // modify your `VStack`
}
}
Alternatively if needed you can extract controls as separate variables:
struct ContentView: View {
var body: some View {
let hstack = HStack {
button
}
return VStack {
hstack
}
}
var button: some View {
Button("Click me") {
// some action
}
}
}
But in the end I definitely recommend you read Apple SwiftUI tutorials
I can't prevent SwiftUI's NavigationLink from being activated when in a List, I have this simple piece of code in which I need to do some kind of business check before deciding to show the details page or not (in a real world app, there might be some business logic happens inside the button's action):
struct ContentView: View {
#State var showDetail = false
var body: some View {
NavigationView {
List {
Text("Text 1")
Text("Text 2")
Text("Text 3")
NavigationLink(destination: DetailView(), isActive: $showDetail) {
LinkView(showDetails: $showDetail)
}
}
}
}
}
struct LinkView: View {
#Binding var showDetails: Bool
var body: some View {
Button(action: {
self.showDetails = false
}) {
Text("Open Details")
}
}
}
struct DetailView: View {
var body: some View {
Text("Detail View")
}
}
how can I prevent navigation link from opening the details page in this case ? and is this a bug in the SDK ?
p.s. XCode version: 13.3.1 and iOS version (real device): 13.3.1
Edit
I can't replace List with ScrollView because I have a ForEach list of items in my real app, so don't post an answer considering using ScrollView.
in a real world app, there might be some business logic happens inside
the button's action
seems to be a little bit alogical.You can simply conditionally disable the link (and inform the user, that the link is unavailable by visual appearance)
NavigationLink(...).disabled(onCondition)
where
func disabled(_ disabled: Bool) -> some View
Parameters
disabled
A Boolean value that determines whether users can interact with this view.
Return Value
A view that controls whether users can interact with this view.
Discussion
The higher views in a view hierarchy can override the value you set on this view. In the following example, the button isn’t interactive because the outer disabled(_:) modifier overrides the inner one:
HStack {
Button(Text("Press")) {}
.disabled(false)
}
.disabled(true)
If I correctly understood your goal, it can be as follows
List {
Text("Text 1")
Text("Text 2")
Text("Text 3")
LinkView(showDetails: $showDetail)
.background(
NavigationLink(destination: DetailView(), isActive: $showDetail) { EmptyView() })
}
and
struct LinkView: View {
#Binding var showDetails: Bool
var body: some View {
Button(action: {
self.showDetails = true // < activate by some logic
}) {
Text("Open Details")
}
}
}
If you use .disable(true) it will reduce your list item opacity like a disabled button, to prevent this. use below code style. Use Navigation Link in backGround and check your navigation condition on Tap Gesture of your view.
VStack{
List(0..<yourListArray.count, id: \.self) { index in
{
Text("\(yourListArr[index].firstName)")
}().onTapGesture{
let jobType = getFlags(jobsArr: yourListArray, index:index)
if jobType.isCancelledFlag == true{
self.shouldNavigate = false
}else{
self.shouldNavigate = true
}
}//Tap Gesture End
.background(NavigationLink(destination: YourDestinationView(),isActive: self.$shouldNavigate) {
}.hidden())}}//vStack
As detailed here (on an iOS topic), the following code can be used to make a SwiftUI View dismiss itself:
#Environment(\.presentationMode) var presentationMode
// ...
presentationMode.wrappedValue.dismiss()
However, this approach doesn't work for a native (not Catalyst) macOS NavigationView setup (such as the below), where the selected view is displayed alongside the List.
Ideally, when any of these sub-views use the above, the list would go back to having nothing selected (like when it first launched); however, the dismiss function appears to do nothing: the view remains exactly the same.
Is this a bug, or expected macOS behaviour?
Is there another approach that can be used instead?
struct HelpView: View {
var body: some View {
NavigationView {
List {
NavigationLink(destination:
AboutAppView()
) {
Text("About this App")
}
NavigationLink(destination:
Text("Here’s a User Guide")
) {
Text("User Guide")
}
}
}
}
}
struct AboutAppView: View {
#Environment(\.presentationMode) var presentationMode
public var body: some View {
Button(action: {
self.dismissSelf()
}) {
Text("Dismiss Me!")
}
}
private func dismissSelf() {
presentationMode.wrappedValue.dismiss()
}
}
FYI: The real intent is for less direct scenarios (such as triggering from an Alert upon completion of a task); the button setup here is just for simplicity.
The solution here is simple. Do not use Navigation View where you need to dismiss the view.
Check the example given by Apple https://developer.apple.com/tutorials/swiftui/creating-a-macos-app
If you need dismissable view, there is 2 way.
Create a new modal window (This is more complicated)
Use sheet.
Following is implimenation fo sheet in macOS with SwiftUI
struct HelpView: View {
#State private var showModal = false
var body: some View {
NavigationView {
List {
NavigationLink(destination:
VStack {
Button("About"){ self.showModal.toggle() }
Text("Here’s a User Guide")
}
) {
Text("User Guide")
}
}
}
.sheet(isPresented: $showModal) {
AboutAppView(showModal: self.$showModal)
}
}
}
struct AboutAppView: View {
#Binding var showModal: Bool
public var body: some View {
Button(action: {
self.showModal.toggle()
}) {
Text("Dismiss Me!")
}
}
}
There is also a 3rd option to use ZStack to create a Modal Card in RootView and change opacity to show and hide with dynamic data.
I am currently using SwiftUI Beta 5. I have a workflow which involves navigating through a series of views. The last view involves an operation which populates a load of data into the app and ends that particular workflow.
Once the data has been downloaded, the user should be able to start new workflow(s). I would like to "forget" about the old NavigationView, since there is no use in going back through the navigation stack once the workflow has completed. Instead, I would like to then navigate to a "launch" view which effectively becomes the root of a new navigation view.
How can one view within a navigation stack be used to navigate to another view with a different NavigationView (and hence becomes a root for a new navigation stack) using SwiftUI NavigagationViews?
First, sorry I wanted to post a simple comment but not enough reputation point :(
I just updated my way to go back to the root you at stackoverflow.com/a/57513566/7786555
You actually gave me the idea with your comment for new way to go back to the root. Having a new root view. If you force the refresh of your struct view managing the root view then it will automatically do what you want. Here under is only going back to the root (without animation). You can adapt the example to change the root view (instead of using the same) to suit your need.
struct DetailViewB: View {
#Environment(\.presentationMode) var presentationMode: Binding<PresentationMode>
#State var fullDissmiss:Bool = false
var body: some View {
SGNavigationChildsView(fullDissmiss: self.fullDissmiss){
VStack {
Text("This is Detail View B.")
Button(action: { self.presentationMode.wrappedValue.dismiss() } )
{ Text("Pop to Detail View A.") }
Button(action: {
self.fullDissmiss = true
} )
{ Text("Pop two levels to Master View with SGGoToRoot.") }
}
}
}
}
struct DetailViewA: View {
#Environment(\.presentationMode) var presentationMode: Binding<PresentationMode>
#State var fullDissmiss:Bool = false
var body: some View {
SGNavigationChildsView(fullDissmiss: self.fullDissmiss){
VStack {
Text("This is Detail View A.")
NavigationLink(destination: DetailViewB() )
{ Text("Push to Detail View B.") }
Button(action: { self.presentationMode.wrappedValue.dismiss() } )
{ Text("Pop one level to Master.") }
Button(action: { self.fullDissmiss = true } )
{ Text("Pop one level to Master with SGGoToRoot.") }
}
}
}
}
struct MasterView: View {
var body: some View {
VStack {
Text("This is Master View.")
NavigationLink(destination: DetailViewA() )
{ Text("Push to Detail View A.") }
}
}
}
struct ContentView: View {
var body: some View {
SGRootNavigationView{
MasterView()
}
}
}
#if DEBUG
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView()
}
}
#endif
struct SGRootNavigationView<Content>: View where Content: View {
let cancellable = NotificationCenter.default.publisher(for: Notification.Name("SGGoToRoot"), object: nil)
let content: () -> Content
init(#ViewBuilder content: #escaping () -> Content) {
self.content = content
}
#State var goToRoot:Bool = false
var body: some View {
return
Group{
if goToRoot == false{
NavigationView {
content()
}
}else{
NavigationView {
content()
}
}
}.onReceive(cancellable, perform: {_ in
DispatchQueue.main.async {
self.goToRoot.toggle()
}
})
}
}
struct SGNavigationChildsView<Content>: View where Content: View {
let notification = Notification(name: Notification.Name("SGGoToRoot"))
var fullDissmiss:Bool{
get{ return false }
set{ if newValue {self.goToRoot()} }
}
let content: () -> Content
init(fullDissmiss:Bool, #ViewBuilder content: #escaping () -> Content) {
self.content = content
self.fullDissmiss = fullDissmiss
}
var body: some View {
return Group{
content()
}
}
func goToRoot(){
NotificationCenter.default.post(self.notification)
}
}
This is how we solved this question: We had a main/root/launch view, from which the user could tap a button to start a business workflow of some kind. This would open a sheet, which would display a modal pop-up view. (The width and height of sheets can be customised, in order to take up most/all of the screen.)
The sheet will have a NavigationView. This would allow the user to step through a series of views as part of their workflow. The "presented" flag gets passed as a binding from the main view to each navigated view.
When the user reaches the last view and taps a Submit/Done/Finish button to end that particular workflow, the "presented" binding can be set to false, which closes the modal pop-up, and returns the user back to the main view.