SwiftUI: Navigate from Sheet to a new View - swiftui

How can I push a new View on the navigation stack from within a Sheet. I want to display a list of Lessons. When tabbing on one of the lessons, a sheet should open showing details about the lesson. From within the Sheet one should be able to start the lesson in a new fullscreen view.
import SwiftUI
struct ContentView: View {
var lessons = [Lesson(id:"1"), Lesson(id:"2"), Lesson(id:"3"), Lesson(id:"4"), Lesson(id:"5"), Lesson(id:"6"), Lesson(id:"7"), Lesson(id:"8"), Lesson(id:"9")]
var body: some View {
NavigationView(){
Form{
List(lessons){ lesson in
LessonButton(lesson: lesson)
}
}
}
}
}
struct LessonButton:View{
#State var showSheet = false
var lesson:Lesson
var body: some View {
Button(action:{self.showSheet = true}){
Text(lesson.name)
}.sheet(isPresented:$showSheet){
NavigationLink(destination: Text("reached")){
Text("start")
}
}
}
}
struct Lesson: Identifiable{
var id:String
var name: String{
"Lesson \(self.id)"
}
}
However the NavigationLink is not working. I guess, this is because the Sheet is not a ChildView of Content View. That's probably why it does not work. But how can it be achieved?

A bit late, but this question came up while solving this. Your sheet acts like its own view controller stack. You can't navigate the parent through the sheet overlay, nor should you. It does seem like you're asking what I was looking for, which is to emulate other apple apps that navigate in sheets. You simply need an additional NavigationView within your sheet. This will give you a navigation stack to push other sheet styled views to the navigation controller within your first sheet.
(SwiftUI beginner, verbiage is likely wrong)
import SwiftUI
struct NavigateFromSheet: View {
var lessons = [Lesson(id:"1"), Lesson(id:"2"), Lesson(id:"3"), Lesson(id:"4"), Lesson(id:"5"), Lesson(id:"6"), Lesson(id:"7"), Lesson(id:"8"), Lesson(id:"9")]
var body: some View {
NavigationView(){
Form {
List(lessons){ lesson in
LessonButton(lesson: lesson)
}
}
}
}
}
struct LessonButton:View{
#State var showSheet = false
var lesson:Lesson
var body: some View {
Button(action:{self.showSheet = true}){
Text(lesson.name)
}.sheet(isPresented: $showSheet){
NavigationView {
VStack {
Text("My First Sheet")
NavigationLink(destination: Text("reached")){
Text("My Second Sheet")
}
}
}
}
}
}
struct Lesson: Identifiable{
var id:String
var name: String{
"Lesson \(self.id)"
}
}
struct NavigateFromSheet_Previews: PreviewProvider {
static var previews: some View {
NavigateFromSheet()
}
}

Sheet is modal view mode, you can enter in it and return back from it.
Actually I can't understand why do you need a sheet in described scenario. As you described it is expected:
List -> Details -> Lesson,
so use consequently two navigation links, one in List, one in Details. This is a native Apple design for NavigationView/NavigationLink usage - navigation from view to view.

Related

Sheet is Only Presented Once in SwiftUI

I have an app which presents a sheet. It works for the first time but when I click on it again it does not work. I am making isPresented false when you dismiss a sheet but when I tap on the Filter button again, it does not show the sheet.
ContentView
struct ContentView: View {
#State private var isPresented: Bool = false
var body: some View {
NavigationView {
List(1...20, id: \.self) { index in
Text("\(index)")
}.listStyle(.plain)
.navigationTitle("Hotels")
.toolbar {
Button("Filters") {
isPresented = true
}
}
.sheet(isPresented: $isPresented) {
isPresented = false
} content: {
FilterView()
}
}
}
}
FilterView:
import SwiftUI
struct FilterView: View {
#Environment(\.presentationMode) private var presentationMode
var body: some View {
ZStack {
Text("FilterView")
Button {
// action
presentationMode.wrappedValue.dismiss()
} label: {
Text("Dismiss")
}
}
}
}
struct FilterView_Previews: PreviewProvider {
static var previews: some View {
FilterView()
}
}
A couple of things to note from my experience.
Firstly, when using the isPresented binding to show a sheet, you don't need to reset the bound value in a custom onDismiss handler to reset it to false - that's handled for you internally by SwiftUI as part of the dismiss action.
So your modifier can be simplified a little:
.sheet(isPresented: $isPresented) {
FilterView()
}
Secondly, when running an app in the Simulator I've noticed that when you come back to the main view after dismissing a sheet you have to interact with the app somehow before clicking on the toolbar button, or the action won't trigger.
In cases like this, just scrolling the list up or down a little would be enough, and then the toolbar button works as you'd expect.
I've not encountered the same thing while running apps on a physical device – whether that's because the bug isn't present, or just that it's a lot easier to interact with the app in some microscopic form of gesture, I couldn't say.

Why the List does not appear?

Why the presetsList does not appear? No errors were thrown though.
import SwiftUI
struct AddMessagePreset: View {
let presetsList = [
Preset(name: "preset text 1"),
Preset(name: "preset text 2"),
Preset(name: "preset text 3")
]
var body: some View {
List(presetsList) { singlePresetModel in
SinglePresetChild (presetModel: singlePresetModel)
}
}
}
import SwiftUI
struct Preset: Identifiable {
let id = UUID()
let name: String
}
struct SinglePresetChild: View {
var presetModel: Preset
var body: some View {
Text("Preset Name \(presetModel.name)")
}
}
UPDATE: To show a List inside another ScrollView (or List), you have to set a height on the inner list view:
struct Preview: View {
var body: some View {
ScrollView {
AddMessagePreset().frame(height: 200)
// more views ...
}
}
}
But let me advise against doing so. Having nested scroll areas can be very confusing for the user.
As discussed in the comments, your component code is fine. However, the way you integrate it into your app causes a problem. Apparently, nesting a List inside a ScrollView does not work properly (also see this thread).
List is already scrollable vertically, so you won't need the additional ScrollView:
struct Preview: View {
var body: some View {
VStack {
AddMessagePreset()
}
}
}
P.S.: If you only want to show AddMessagePreset and won't add another sibling view, you can remove the wrapping VStack; or even show AddMessagePreset as the main view, without any wrapper.

SwiftUI Navigation popping back when modifying list binding property in a pushed view

When I update a binding property from an array in a pushed view 2+ layers down, the navigation pops back instantly after a change to the property.
Xcode 13.3 beta, iOS 15.
I created a simple demo and code is below.
Shopping Lists
List Edit
List section Edit
Updating the list title (one view deep) is fine, navigation stack stays same, and changes are published if I return. But when adjusting a section title (two deep) the navigation pops back as soon as I make a single change to the property.
I have a feeling I'm missing basic fundamentals here, and I have a feeling it must be related to the lists id? but I'm struggling to figure it out or work around it.
GIF
Code:
Models:
struct ShoppingList {
let id: String = UUID().uuidString
var title: String
var sections: [ShoppingListSection]
}
struct ShoppingListSection {
let id: String = UUID().uuidString
var title: String
}
View Model:
final class ShoppingListsViewModel: ObservableObject {
#Published var shoppingLists: [ShoppingList] = [
.init(
title: "Shopping List 01",
sections: [
.init(title: "Fresh food")
]
)
]
}
Content View:
struct ContentView: View {
var body: some View {
NavigationView {
ShoppingListsView()
}
}
}
ShoppingListsView
struct ShoppingListsView: View {
#StateObject private var viewModel = ShoppingListsViewModel()
var body: some View {
List($viewModel.shoppingLists, id: \.id) { $shoppingList in
NavigationLink(destination: ShoppingListEditView(shoppingList: $shoppingList)) {
Text(shoppingList.title)
}
}
.navigationBarTitle("Shopping Lists")
}
}
ShoppingListEditView
struct ShoppingListEditView: View {
#Binding var shoppingList: ShoppingList
var body: some View {
Form {
Section(header: Text("Title")) {
TextField("Title", text: $shoppingList.title)
}
Section(header: Text("Sections")) {
List($shoppingList.sections, id: \.id) { $section in
NavigationLink(destination: ShoppingListSectionEditView(section: $section)) {
Text(section.title)
}
}
}
}
.navigationBarTitle("Edit list")
}
}
ShoppingListSectionEditView
struct ShoppingListSectionEditView: View {
#Binding var section: ShoppingListSection
var body: some View {
Form {
Section(header: Text("Title")) {
TextField("title", text: $section.title)
}
}
.navigationBarTitle("Edit section")
}
}
try this, works for me:
struct ContentView: View {
var body: some View {
NavigationView {
ShoppingListsView()
}.navigationViewStyle(.stack) // <--- here
}
}
Try to make you object confirm to Identifiable and return value which unique and stable, for your case is ShoppingList.
Detail view seems will pop when object id changed.
The reason your stack is popping back to the root ShoppingListsView is that the change in the list is published and the root ShoppingListsView is registered to listen for updates to the #StateObject.
Therefore, any change to the list is listened to by ShoppingListsView, causing that view to be re-rendered and for all new views on the stack to be popped in order to render the root ShoppingListsView, which is listening for updates on the #StateObject.
The solution to this is to change the #StateObject to #EnvironmentObject
Please refactor your code to change ShoppingListsViewModel to use an #EnvironmentObject wrapper instead of a #StateObject wrapper
You may pass the environment object in to all your child views and also add a boolean #Published flag to track any updates to the data.
Then your ShoppingListView would look as below
struct ShoppingListsView: View {
#EnvironmentObject var viewModel = ShoppingListsViewModel()
var body: some View {
List($viewModel.shoppingLists, id: \.id) { $shoppingList in
NavigationLink(destination: ShoppingListEditView(shoppingList: $shoppingList)) {
Text(shoppingList.title)
}
}
.navigationBarTitle("Shopping Lists")
}
}
Don't forget to pass the viewModel in to all your child views.
That should fix your problem.

SwiftUI NavigationLink

I'm working on a SwiftUI practice app and I ran into an issue with the NavigationView/NavigationLink. I am currently using the Metropolitan Museum of Art API and I wanted to make a list of departments that segues to another list of objects in that department, then that list segues to the object's information. Currently the NavigationView/NavigationLink setup I have is creating multiple NavigationViews and is resulting in multiple back buttons/navigation bars. Is there a way to have the new NavigationView replace the old one or have them work in line with one another? The only way I know how to create a segue in SwiftUI is through a NavigationView/NavigationLink but creating it twice seems to be the wrong way to go about things. I have a screen shot of the current state of my app.
App Image
This is my code at the moment.
struct ContentView: View {
#ObservedObject var model = DepartmentListViewModel()
var body: some View {
NavigationView {
List {
ForEach(model.departments, id: \.self) { department in
NavigationLink(destination: DetailView(viewModel: DetailListViewModel(selectedDepartment: department))) {
Text(department.displayName)
}
}
}
.navigationBarTitle("Departments")
}
}
}
struct DetailView: View {
#ObservedObject var viewModel: DetailListViewModel
init(viewModel: DetailListViewModel) {
self.viewModel = viewModel
}
var body: some View {
NavigationView {
List {
ForEach(viewModel.objects, id: \.self) { object in
NavigationLink(destination: ObjectView(viewModel: ObjectListViewModel(selectedObject: object))) {
Text(String(object))
}
}
}
.navigationBarTitle("ObjectIDs")
}
}
}
You don't need NavigationView in your DetailView anymore, the first one handle it

Disable drag to dismiss in SwiftUI Modal

I've presented a modal view but I would like the user to go through some steps before it can be dismissed.
Currently the view can be dragged to dismiss.
Is there a way to stop this from being possible?
I've watched the WWDC Session videos and they mention it but I can't seem to put my finger on the exact code I'd need.
struct OnboardingView2 : View {
#Binding
var dismissFlag: Bool
var body: some View {
VStack {
Text("Onboarding here! 🙌🏼")
Button(action: {
self.dismissFlag.toggle()
}) {
Text("Dismiss")
}
}
}
}
I currently have some text and a button I'm going to use at a later date to dismiss the view.
iOS 15+
Starting from iOS 15 we can use interactiveDismissDisabled:
func interactiveDismissDisabled(_ isDisabled: Bool = true) -> some View
We just need to attach it to the sheet. Here is an example from the documentation:
struct PresentingView: View {
#Binding var showTerms: Bool
var body: some View {
AppContents()
.sheet(isPresented: $showTerms) {
Sheet()
}
}
}
struct Sheet: View {
#State private var acceptedTerms = false
var body: some View {
Form {
Button("Accept Terms") {
acceptedTerms = true
}
}
.interactiveDismissDisabled(!acceptedTerms)
}
}
It is easy if you use the 3rd party lib Introspect, which is very useful as it access the corresponding UIKit component easily. In this case, the property in UIViewController:
VStack { ... }
.introspectViewController {
$0.isModalInPresentation = true
}
Not sure this helps or even the method to show the modal you are using but when you present a SwiftUI view from a UIViewController using UIHostingController
let vc = UIHostingController(rootView: <#your swiftUI view#>(<#your parameters #>))
you can set a modalPresentationStyle. You may have to decide which of the styles suits your needs but .currentContext prevents the dragging to dismiss.
Side note:I don't know how to dismiss a view presented from a UIHostingController though which is why I've asked a Q myself on here to find out 😂
I had a similar question here
struct Start : View {
let destinationView = SetUp()
.navigationBarItem(title: Text("Set Up View"), titleDisplayMode: .automatic, hidesBackButton: true)
var body: some View {
NavigationView {
NavigationButton(destination: destinationView) {
Text("Set Up")
}
}
}
}
The main thing here is that it is hiding the back button. This turns off the back button and makes it so the user can't swipe back ether.
For the setup portion of your app you could create a new SwiftUI file and add a similar thing to get home, while also incorporating your own setup code.
struct SetUp : View {
let destinationView = Text("Your App Here")
.navigationBarItem(title: Text("Your all set up!"), titleDisplayMode: .automatic, hidesBackButton: true)
var body: some View {
NavigationView {
NavigationButton(destination: destinationView) {
Text("Done")
}
}
}
}
There is an extension to make controlling the modal dismission effortless, at https://gist.github.com/mobilinked/9b6086b3760bcf1e5432932dad0813c0
A temporary solution before the official solution released by Apple.
/// Example:
struct ContentView: View {
#State private var presenting = false
var body: some View {
VStack {
Button {
presenting = true
} label: {
Text("Present")
}
}
.sheet(isPresented: $presenting) {
ModalContent()
.allowAutoDismiss { false }
// or
// .allowAutoDismiss(false)
}
}
}