I have a list in a Navigation View, with a trailing navigation button to add a list item. The button opens a modal sheet. When I dismiss the sheet (by pulling it down), the sheet pops right back up again automatically and I can't get back to the first screen. Here's my code.
struct ListView: View {
#ObservedObject var listVM: ListViewModel
#State var showNewItemView: Bool = false
init() {
self.listVM = ListViewModel()
}
var body: some View {
NavigationView {
List {
ForEach(listVM.items, id: \.dateCreated) { item in
HStack {
Text(item.name)
Spacer()
Image(systemName: "arrow.right")
}
}
}
.navigationBarTitle("List Name")
.navigationBarItems(trailing: AddNewItemBtn(isOn: $showNewItemView))
}
}
}
struct AddNewItemBtn: View {
#Binding var isOn: Bool
var body: some View {
Button(
action: { self.isOn.toggle() },
label: { Image(systemName: "plus.app") })
.sheet(
isPresented: self.$isOn,
content: { NewItemView() })
}
}
I am getting this error:
Warning: Attempt to present <_TtGC7SwiftUIP13$7fff2c603b7c22SheetHostingControllerVS_7AnyView_: 0x7fc5e0c1f8f0> on which is already presenting (null)
I've tried toggling the bool within "onDismiss" on the button itself, but that doesn't work either. Any ideas?
Turns out putting the button in the navigationBarItems(trailing:) modifier is the problem. I just put the button in the list itself instead of in the nav bar and it works perfectly fine. Must be some kind of bug.
Related
So I am writing a todo list app in SwiftUI in order to get the hang of it, but I am facing a problem.
In my first view (list of items) I have a toolbar with an "add" button which uses a NavigationLink to navigate to the detail view. In the detail view I also have a toolbar button acting as a save button which dismisses this view and also adds the item to a list of items kept in the view model used by both views.
The problem is that if I save the item when tapping the save button it will first navigate back to the first view and then auto navigate to the second view again. If I instead use the built in back button this issue doesn't happen, but obviously I would like to save the item and only when pressing save. This also only happens if I add the item to the item list in the view model before dismissing the view, if I only dismiss the view without saving the item when pressing done then this bug doesn't happen.
Is this not a standard way of saving and closing a view with SwiftUI, or is there some sort of other pattern that is better? In any case I need to resolve this issue.
First view:
struct TodoListView: View {
#EnvironmentObject var viewModel: TodoListViewModel
var body: some View {
NavigationView {
List {
ForEach(viewModel.listOfTodos) { todoItem in
ItemCellView(todoItem: todoItem)
}
}
.navigationTitle("Things to do")
.toolbar {
ToolbarItem(placement: .navigationBarTrailing) {
NavigationLink(
destination: AddEditTodoView(todoItem: TodoListInfo.TodoItem())
) {
Text("Add item") // The navigation bug happens when using this button
}
}
}
}
.navigationViewStyle(StackNavigationViewStyle())
}
}
struct ItemCellView: View {
var todoItem: TodoListInfo.TodoItem
var body: some View {
HStack {
NavigationLink(destination: AddEditTodoView(todoItem: todoItem)) {
Text(todoItem.title) // The navigation bug doesn't happen when editing an existing item
}
}
.padding()
}
}
Second view:
struct AddEditTodoView: View {
#Environment(\.presentationMode) var presentationMode: Binding<PresentationMode>
#EnvironmentObject var viewModel: TodoListViewModel
#State var todoItem: TodoListInfo.TodoItem
var body: some View {
Form {
Section(header: Text("Title")) {
TextField("Title", text: $todoItem.title)
}
}
.navigationTitle(Text("Edit task"))
.toolbar {
ToolbarItem(placement: .navigationBarTrailing) {
Button("Done") {
viewModel.upsert(item: todoItem) // No bug if I comment out this line
presentationMode.wrappedValue.dismiss()
}
.disabled(todoItem.title == "")
}
}
}
}
View model:
class TodoListViewModel: ObservableObject {
#Published private var todoListInfo: TodoListInfo
private var autoSaveCancellable: AnyCancellable? // even without the autoSaveCancellable part, the bug happens
init(testData: Bool = false) {
todoListInfo = TodoListInfo(testData: testData)
autoSaveCancellable = $todoListInfo.sink {
TodoListInfo.persistTodoList($0)
}
}
var listOfTodos: [TodoListInfo.TodoItem] {
todoListInfo.todos
}
func upsert(item: TodoListInfo.TodoItem) {
if let itemIndex = todoListInfo.todos.firstIndex(where: { $0.id == item.id }) {
todoListInfo.todos[itemIndex] = item
} else {
todoListInfo.todos.append(item) // This gets called when adding an item
}
}
}
The solution for this is to make the navigation be based on a binding state.
NavigationLink(
destination: ExchangeItemSelectedView(exchange: observer),
tag: exchange.id,
selection: $exchangeSelection
) {
Text("Tap Me")
}
then rather than using #State to store exchangeSelection use #SceneStorage this will let you access the binding from anywhere within your app, in the code that creates the new item it should then dispatch async to update the selection value to the new item ID.
I have two views, one leads to the other. I want that the second view uses the title of the first view for the back button, which should then be: "<View1".
I don't want to show the title in the first view.
Problem: I can't hide navigation bar because it will also hide a custom button which is within it. Setting .navigationTitle("") hides the title in the first view, but also hides it from the back button in the second view.
What I have now:
What I would like to have:
Code:
struct ContentView: View {
#State var isLinkActive = false
var body: some View {
NavigationView {
VStack {
NavigationLink("go to the second view", destination: SecondView(), isActive: $isLinkActive).navigationTitle("View1")
.navigationBarItems(leading: Button(action: {
()
}, label: {
Text("custom button")
}))
}
}.navigationViewStyle(StackNavigationViewStyle())
}
private func btnPressed() {
isLinkActive = true
}
}
struct SecondView: View {
var body: some View {
Color.blue
}
}
You need to create custom back button for destination view as well,and you shouldn’t set navigation title for navigationLink, that’s why you are not able to hide “View1” correctly.
Check below code.
import SwiftUI
struct Test: View {
#State var isLinkActive = false
var body: some View {
NavigationView {
VStack {
NavigationLink("go to the second view", destination: SecondView()
.navigationBarBackButtonHidden(true)
.navigationBarItems(leading: Button(action: {
isLinkActive = false
}, label: {
HStack{
Image(systemName: "backward.frame.fill")
Text("View1")
}
})) ,
isActive: $isLinkActive)
}.navigationBarItems(leading: Button(action: {
()
}, label: {
Text("custom button")
}))
}.navigationViewStyle(StackNavigationViewStyle())
}
private func btnPressed() {
isLinkActive = true
}
}
struct SecondView: View {
var body: some View {
Color.blue
}
}
You can try and make navigationBar code as reusable component, because you might need to do this at multiple places.
Output-:
I achieved this by using two modifiers on my main view. Similar to your case, I didn't want a title on the first view, but I wanted the back button on the pushed view to read < Home, not < Back.
.navigationTitle("Home")
.toolbar {
ToolbarItem(placement: .principal) {
Text("")
}
}
Whenever my code gets too big, SwiftUI starts acting weird and generates an error:
"The compiler is unable to type-check this expression in reasonable time; try breaking up the expression into distinct sub-expressions"
So I started breaking up my code into Extracted Subviews, one of the problems I came across is how to dismiss a view from a subtracted subview.
Example: we have here LoginContentView this view contains a button when the button is clicked it will show the next view UsersOnlineView.
struct LoginContentView: View {
#State var showUsersOnlineView = false
var body: some View {
Button(action: {
self.showUsersOnlineView = true
}) {
Text("Show the next view")
}
.fullScreenCover(isPresented: $showUsersOnlineView, content: {
UsersOnlineView()
})
}
On the other hand, we have a button that is extracted to subview, to dismiss the modal and go back to the original view:
import SwiftUI
struct UsersOnlineView: View {
var body: some View {
ZStack {
VStack {
CloseViewButton()
}
}
}
}
struct CloseViewButton: View {
var body: some View {
Button(action: {
// Close the Modal
}) {
Text("Close the view")
}
}
}
Give the sbview the state property that defines if the view is shown.
struct CloseViewButton: View {
#Binding var showView: Bool
var body: some View {
Button(
ShowView = false
}) {
Text("Close the view")
}
}
}
When you use the sub view give it the property
CloseButtonView(showView: $showOnlineView)
To allow the sub view to change the isShown property it needs to get a binding.
On the presentation mode. I think this only works with Swiftui presentations like sheet and alert.
The simplest solution for this scenario is to use presentationMode environment variable:
struct CloseViewButton: View {
#Environment(\.presentationMode) var presentationMode
var body: some View {
Button(action: {
presentationMode.wrappedValue.dismiss()
}) {
Text("Close the view")
}
}
}
Tested with Xcode 12.1 / iOS 14.1
I want to detect if the user meets the prerequisite first before I let him/her in. If the prerequisite is not met, the app will pop an actionSheet and show the user some ways to unlock the feature.
It works perfectly fine when I tap on the text. But when I tap on the blank place on the list. It just skip the Binding. And the weird thing is that in my actually project, the Binding becomes "true" even if I only set it to false.
Here's the question. Am I using the correct approach or did I miss anything? Or is this a bug?
Thank you.
struct ContentView: View {
#State var linkOne = false
#State var linkTwo = false
#State var linkThree = false
#State var actionOne = false
#State var actionTwo = false
#State var actionThree = false
var body: some View {
NavigationView{
List{
NavigationLink("Destination View One", destination: DestOneView(), isActive: self.$linkOne)
.actionSheet(isPresented: self.$actionOne) { () -> ActionSheet in
ActionSheet(title: Text("Hello"), message:Text("This is weird"), buttons: [ActionSheet.Button.cancel()])
}.onTapGesture {
self.actionOne = true
// self.linkOne = true
}
NavigationLink("Destination View Two", destination: DestTwoView(), isActive: self.$linkTwo)
.actionSheet(isPresented: self.$actionTwo) { () -> ActionSheet in
ActionSheet(title: Text("Hello"), message:Text("This is weird"), buttons: [ActionSheet.Button.cancel()])
}
.onTapGesture {
self.actionTwo = true
// self.linkTwo = true
}
NavigationLink("Destination View Three", destination: DestThreeView(), isActive: self.$linkThree)
.actionSheet(isPresented: self.$actionThree) { () -> ActionSheet in
ActionSheet(title: Text("Hello"), message:Text("This is weird"), buttons: [ActionSheet.Button.cancel()])
}
.onTapGesture {
self.actionThree = true
// self.linkThree = true
}
}
}
}
}
Three other views.
struct DestOneView: View {
var body: some View {
Text("First View")
}
}
struct DestTwoView: View {
var body: some View {
Text("Second View")
}
}
struct DestThreeView: View {
var body: some View {
Text("Third View")
}
}
Generally overriding gestures does not work well within the List. One of the solutions can be to use a Button to present a NavigationLink:
import SwiftUI
struct ContentView: View {
#State private var linkOne = false
...
var body: some View {
NavigationView {
List {
NavigationLink(destination: SomeView(), isActive: $linkOne) {
EmptyView()
}
Button(action: {
// here you can perform actions
self.linkOne = true
}, label: {
Text("Some text!")
})
Spacer()
}
}
}
}
When I came back and tested my the code. The solution didn't really work. May be because of the List's bug. People on another post said that the List in the new view only show once if the sheet is inside the List. So I only got an empty List in the new view when I tap the button in Xcode Version 11.5. For some reasion, if I use NavigationView, all contents are shrunk into the middle of the view instead of aligning to the top.
My work around is to set the Binding in .onAppear. It pops the actionSheet when the view loads. And then use the presentationMode method to return to the previous view.
#Environment(\.presentationMode) var presentationMode
.
.
.
ActionSheet.Button.default(Text("Dismiss"), action: {
self.presentationMode.wrappedValue.dismiss()}
Here is a bug in SwiftUI when you show modal from button inside navigation bar items.
In code below Button 1 works as expected, but Button 2 works only once:
struct DetailView: View {
#Binding var isPresented: Bool
#Environment (\.presentationMode) var presentationMode
var body: some View {
NavigationView {
Text("OK")
.navigationBarTitle("Details")
.navigationBarItems(trailing: Button(action: {
self.isPresented = false
// or:
// self.presentationMode.wrappedValue.dismiss()
}) {
Text("Done").bold()
})
}
}
}
struct ContentView: View {
#State var showSheetView = false
var body: some View {
NavigationView {
Group {
Text("Master")
Button(action: { self.showSheetView.toggle() }) {
Text("Button 1")
}
}
.navigationBarTitle("Main")
.navigationBarItems(trailing: Button(action: {
self.showSheetView.toggle()
}) {
Text("Button 2").bold()
})
}.sheet(isPresented: $showSheetView) {
DetailView(isPresented: self.$showSheetView)
}
}
}
This bug is from the middle of the last year, and it still in Xcode 11.3.1 + iOS 13.3 Simulator and iOS 13.3.1 iPhone XS.
Is here any workaround to make button work?
EDIT:
Seems to be tap area goes somewhere down and it's possible to tap below button to show modal.
Temporary solution to this is to use inline navigation bar mode:
.navigationBarTitle("Main", displayMode: .inline)
Well, the issue is in bad layout (seems broken constrains) of navigation bar button after sheet has closed
It is clearly visible in view hierarchy debug:
Here is a fix (workaround of course, but safe, because even after issue be fixed it will continue working). The idea is not to fight with broken layout but just create another button, so layout engine itself remove old-bad button and add new one refreshing layout. The instrument for this is pretty known - use .id()
So modified code:
struct ContentView: View {
#State var showSheetView = false
#State private var navigationButtonID = UUID()
var body: some View {
NavigationView {
Group {
Text("Master")
Button(action: { self.showSheetView.toggle() }) {
Text("Button 1")
}
}
.navigationBarTitle("Main")
.navigationBarItems(trailing: Button(action: {
self.showSheetView.toggle()
}) {
Text("Button 2").bold() // recommend .padding(.vertical) here
}
.id(self.navigationButtonID)) // force new instance creation
}
.sheet(isPresented: $showSheetView) {
DetailView(isPresented: self.$showSheetView)
.onDisappear {
// update button id after sheet got closed
self.navigationButtonID = UUID()
}
}
}
}