Different Section Header Style in ChildView - swiftui

I use a Form which gives me the following Section-Header-Style:
As a ChildView, I want to display a list with different sections. However, the section header is wrong/broken and is not sticky as it is supposed to be. It should look like this:
If I change the the Form to a List both header styles become sticky.
How can I have Form-Headers in the ParentView but List (sticky) headers in the ChildView?
Here is some sample code:
struct ContentView: View {
var body: some View{
NavigationView{
// change to List for different Section Header Style
Form{
Section(header: Text("Section Style 1")){
NavigationLink(destination: ChildView()){ Text("Go to Child") }
}
}
.navigationBarTitle("Section Style")
}
}
}
struct ChildView:View{
var items:[Item] = []
init(){
self.items = [Item(id:1), Item(id:2), Item(id:3), Item(id:4), Item(id:5), Item(id:6), Item(id:7), Item(id:8)]
}
var body: some View{
List{
Section(header:Text("Sticky Header Style")){
ForEach(self.items, id:\.id){item in
Text(String(item.id))
}
}
}
}
}
struct Item {
var id: Int
}

You need to use PlainListStyle as below
struct ChildView:View{
var items:[Item] = []
init(){
self.items = [Item(id:1), Item(id:2), Item(id:3), Item(id:4), Item(id:5), Item(id:6), Item(id:7), Item(id:8)]
}
var body: some View{
List{
Section(header:Text("Sticky Header Style")){
ForEach(self.items, id:\.id){item in
Text(String(item.id))
}
}
}.listStyle(PlainListStyle()) // << here is a fix !
}
}

Related

SwiftUI, How to Use Programmatic Navigation Using Value, with different NavigationDestinations

I am struggling to get my head around how to use programmatic navigation with multiple destination views which take the same type of value. In the following code I can successfully navigate from ContentView to View2, but would like to navigate from View2 to View3 by adding a value to the path.
The navigationDestination in ContentView has View2 specified. How/where do I add a second navigationDestination to View3? If I add a navigationDestination in View2 pointing to View3 then it doesn't work, as it uses the View1's navigationDestination as it is closer to root. I would appreciate some guidance on how to approach this problem. Many thanks in advance.
struct ContentView: View {
#State private var path = NavigationPath()
var body: some View {
NavigationStack(path: $path) {
NavigationLink(value: "view2") {
Text("Go to View2")
}
.navigationDestination(for: String.self) { destination in
View2(someParameterA: destination)
}
.navigationTitle("ContentView")
}
}
}
struct View2: View {
#State var someParameterA: String
var body: some View {
VStack {
Text(someParameterA)
NavigationLink(value: "view3") {
Text("Go to View3")
}
}
.navigationTitle("View 2")
}
}
struct View3: View {
#State var someParameterB: String
var body: some View {
Text(someParameterB)
.navigationTitle("View 3")
}
}
I've managed to hack the following solution together which works but is there a better approach?
enum DestinationView {
case view2
case view3
}
struct NavStruct: Equatable, Hashable {
var destinationView: DestinationView
var param: String
}
class ViewSelector {
#ViewBuilder
static func viewForDestination(_ destination: DestinationView, _ param: String) -> some View {
switch destination {
case .view2:
View2(someParameterA: param)
case .view3:
View3(someParameterB: param)
}
}
}
struct ContentView: View {
#State private var path = NavigationPath()
var body: some View {
NavigationStack(path: $path) {
NavigationLink(value: NavStruct(destinationView: .view2, param: "view2")) {
Text("Go to View2")
}
.navigationDestination(for: NavStruct.self) { destination in
ViewSelector.viewForDestination(destination.destinationView, destination.param)
}
.navigationTitle("ContentView")
}
}
}
struct View2: View {
#State var someParameterA: String
var body: some View {
VStack {
Text(someParameterA)
NavigationLink(value: NavStruct(destinationView: .view3, param: "view3")) {
Text("Go to View3")
}
}
.navigationTitle("View 2")
}
}
struct View3: View {
#State var someParameterB: String
var body: some View {
VStack {
Text(someParameterB)
}
.navigationTitle("View 3")
}
}

SwiftUI .sheet Unexpectedly found nil while unwrapping an Optional value

The Problem
The following example highlights my issue better than I can explain it. I explicitly give an optional variable a value before presenting a sheet. This sheet, which requires a non-optional variable to init, doesn't register the value and says it is nil. I can't understand why this would be if I only ever call the sheet after the optional has been given a value. Any help would be greatly appreciated. Thanks!
What I have tried
In the example I replaced:
.sheet(isPresented: $showModalView, content: {
EditBookView(book: editingBook!) //Fatal error here
})
with:
.sheet(isPresented: $showModalView, content: {
if let book = editingBook {
EditBookView(book: book)
}
})
However, this just shows an empty sheet (implying that editingBook is empty). But, interestingly when I close this empty sheet and select another item in the list, the view appears as intended.
Reproducible example
import SwiftUI
struct Book: Identifiable {
var id: UUID
var title: String
init(title: String){
self.title = title
self.id = UUID()
}
}
struct ContentView: View {
#State var books = [Book]()
#State var showModalView = false
#State var editingBook: Book? = nil
var body: some View {
List{
ForEach(books){ book in
VStack(alignment: .leading){
Text(book.title)
.font(Font.title.bold())
Text("id: \(book.id.uuidString)")
.foregroundColor(.gray)
Button(action: {
editingBook = book
showModalView = true
}){
Text("Edit")
.foregroundColor(.accentColor)
}
.buttonStyle(PlainButtonStyle())
.padding(.top)
}
}
}
.padding()
.onAppear{
for i in 0...50 {
books.append(Book(title: "Book #\(i)"))
}
}
.sheet(isPresented: $showModalView, content: {
EditBookView(book: editingBook!) //Fatal error here
})
}
}
struct EditBookView: View {
var book: Book
var body: some View {
Text(book.title)
}
}
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView()
}
}
Edit:
enum SheetChoice: Hashable, Identifiable {
case addContentView
case editContentView
var id: SheetChoice { self }
}
...
.sheet(item: $sheetChoice){ item in
switch item {
case .addContentView:
AddContentView()
.environmentObject(model)
case .editContentView:
//if let selectedContent = selectedContent {
ContentEditorView(book: selectedContent!, editingFromDetailView: false)
.environmentObject(model)
//}
}
}
Make sure you also use editingBook inside your body (not only sheet building block).
SwiftUI tracks which State variables are used in its body. When it’s not used, you might come into this weird situations when your body is called with ignored changes to that state variable.
So basically add this line at the beginning of your body:
var body: some View {
_ = editingBook
return <your view>
}
Alternatively, you can use this .sheet modifier version:
https://developer.apple.com/documentation/swiftui/view/sheet(item:ondismiss:content:)
Following the answer from #msmialko, I suspect this is a compiler problem.
_ = self.<your_variable>
inside body solves the problem.
One possible workaround is moving out the sheet content into another View, and pass the Binding to the #Stete to it:
struct Book: Identifiable {
var id: UUID
var title: String
init(title: String){
self.title = title
self.id = UUID()
}
}
enum SheetChoice: Hashable, Identifiable {
case addContentView
case editContentView
var id: SheetChoice { self }
}
class MyModel: ObservableObject {
}
struct ContentView: View {
#State var books = [Book]()
#State var selectedContent: Book? = nil
#State var sheetChoice: SheetChoice? = nil
#StateObject var model = MyModel()
var body: some View {
List{
ForEach(books){ book in
VStack(alignment: .leading){
Text(book.title)
.font(Font.title.bold())
Text("id: \(book.id.uuidString)")
.foregroundColor(.gray)
Button(action: {
selectedContent = book
sheetChoice = .editContentView
}){
Text("Edit")
.foregroundColor(.accentColor)
}
.buttonStyle(PlainButtonStyle())
.padding(.top)
}
}
}
.padding()
.onAppear{
for i in 0...50 {
books.append(Book(title: "Book #\(i)"))
}
}
.sheet(item: $sheetChoice){
item in
SheetContentView(item: item, selectedContent: $selectedContent)
.environmentObject(model)
}
}
}
struct SheetContentView: View {
var item: SheetChoice
var selectedContent: Binding<Book?>
var body: some View {
switch item {
case .addContentView:
AddContentView()
case .editContentView:
ContentEditorView(book: selectedContent.wrappedValue!,
editingFromDetailView: false)
}
}
}
struct ContentEditorView: View {
var book: Book
var editingFromDetailView: Bool
var body: some View {
Text(book.title)
}
}
struct AddContentView: View {
var body: some View {
Text("AddContentView")
}
}

How to edit an item in a list using NavigationLink?

I am looking for some guidance with SwiftUI please.
I have a view showing a simple list with each row displaying a "name" string. You can add items to the array/list by clicking on the trailing navigation bar button. This works fine. I would now like to use NavigationLink to present a new "DetailView" in which I can edit the row's "name" string. I'm struggling with how to use a binding in the detailview to update the name.
I've found plenty of tutorials online on how to present data in the new view, but nothing on how to edit the data.
Thanks in advance.
ContentView:
struct ListItem: Identifiable {
let id = UUID()
let name: String
}
class MyListClass: ObservableObject {
#Published var items = [ListItem]()
}
struct ContentView: View {
#ObservedObject var myList = MyListClass()
var body: some View {
NavigationView {
List {
ForEach(myList.items) { item in
NavigationLink(destination: DetailView(item: item)) {
Text(item.name)
}
}
}
.navigationBarItems(trailing:
Button(action: {
let item = ListItem(name: "Test")
self.myList.items.append(item)
}) {
Image(systemName: "plus")
}
)
}
}
}
DetailView
struct DetailView: View {
var item: ListItem
var body: some View {
TextField("", text: item.name)
}
}
The main idea that you pass in DetailsView not item, which is copied, because it is a value, but binding to the corresponding item in your view model.
Here is a demo with your code snapshot modified to fulfil the requested behavior:
struct ListItem: Identifiable, Equatable {
var id = UUID()
var name: String
}
class MyListClass: ObservableObject {
#Published var items = [ListItem]()
}
struct ContentView: View {
#ObservedObject var myList = MyListClass()
var body: some View {
NavigationView {
List {
ForEach(myList.items) { item in
// Pass binding to item into DetailsView
NavigationLink(destination: DetailView(item: self.$myList.items[self.myList.items.firstIndex(of: item)!])) {
Text(item.name)
}
}
}
.navigationBarItems(trailing:
Button(action: {
let item = ListItem(name: "Test")
self.myList.items.append(item)
}) {
Image(systemName: "plus")
}
)
}
}
}
struct DetailView: View {
#Binding var item: ListItem
var body: some View {
TextField("", text: self.$item.name)
}
}

Remove the text from back button in SwiftUI

In short, I want to do this, but with SwiftUI.
(Home should be removed)
So far, I have not found a way to access the NavigationBarButton directly, and have managed to find the following that appears to be the only way I can find to date for modifying the button:
struct MyList: View {
var body: some View {
Text("MyList")
.navigationBarTitle(Text(verbatim: "MyList"), displayMode: .inline)
.navigationBarItems(leading: Text("<"))
}
}
However, I lose the default return image and get an ugly < instead.
You need to set the title of the view that the back button will pop to:
struct ContentView: View {
var body: some View {
NavigationView {
VStack {
NavigationLink(destination: DetailView()) {
Text("push view")
}
}.navigationBarTitle("", displayMode: .inline)
}
}
}
struct DetailView: View {
var body: some View {
Text("Detail View")
}
}
Alternatively, to conditionally set or unset the title of the source view, depending on the presentation status you can use the code below.
Beware that the isActive parameter has a bug, but that will most likely be solved soon. Here's a reference to the bug mentioned SwiftUI: NavigationDestinationLink deprecated
struct ContentView: View {
#State private var active: Bool = false
var body: some View {
NavigationView {
VStack {
NavigationLink(destination: DetailView(), isActive: $active) {
Text("push view")
}
}.navigationBarTitle(!active ? "View Title" : "", displayMode: .inline)
}
}
}
struct DetailView: View {
var body: some View {
Text("Detail View")
}
}
Works on iOS 16
Since you can update NavigationItem inside the init of the View. You can solve this in 2 steps:
Get visible View Controller.
// Get Visible ViewController
extension UIApplication {
static var visibleVC: UIViewController? {
var currentVC = UIApplication.shared.windows.first { $0.isKeyWindow }?.rootViewController
while let presentedVC = currentVC?.presentedViewController {
if let navVC = (presentedVC as? UINavigationController)?.viewControllers.last {
currentVC = navVC
} else if let tabVC = (presentedVC as? UITabBarController)?.selectedViewController {
currentVC = tabVC
} else {
currentVC = presentedVC
}
}
return currentVC
}
}
Update NavigationItem inside init of the View.
struct YourView: View {
init(hideBackLabel: Bool = true) {
if hideBackLabel {
// iOS 14+
UIApplication.visibleVC?.navigationItem.backButtonDisplayMode = .minimal
// iOS 13-
let button = UIBarButtonItem(title: "", style: .plain, target: nil, action: nil)
UIApplication.visibleVC?.navigationItem.backBarButtonItem = button
}
}
}

How to disable NavigationView push and pop animations

Given this simple NavigationView:
struct ContentView : View {
var body: some View {
NavigationView {
VStack {
NavigationLink("Push Me", destination: Text("PUSHED VIEW"))
}
}
}
}
Did anyone find a way of disabling the NavigationView animation when a destination view is pushed/popped into/from the stack?
This has been possible in UIKit since iOS2.0! I think it is not too much to ask from the framework. I tried all sorts of modifiers on all views (i.e., the NavigationView container, the destination view, the NavigationLink, etc)
These are some of the modifiers I tried:
.animation(nil)
.transition(.identity)
.transaction { t in t.disablesAnimations = true }
.transaction { t in t.animation = nil }
None made a difference. I did not find anything useful in the EnvironmentValues either :-(
Am I missing something very obvious, or is the functionality just not there yet?
Xcode 11.3:
Right now there is no modifier to disable NavigationView animations.
You can use your struct init() to disable animations, as below:
struct ContentView : View {
init(){
UINavigationBar.setAnimationsEnabled(false)
}
var body: some View {
NavigationView {
VStack {
NavigationLink("Push Me", destination: Text("PUSHED VIEW"))
}
}
}
}
First you need state for the NavigationLink to respond to, then set that state inside a transaction with animations disabled, as follows:
struct ContentView : View {
#State var isActive = false
var body: some View {
NavigationView {
VStack {
NavigationLink(isActive: $isActive, destination: {
Text("PUSHED VIEW")}) {
Text("Push Me")
}
Button("Navigate Without Animation") {
var transaction = Transaction()
transaction.disablesAnimations = true
withTransaction(transaction) {
isActive = true
}
}
}
}
}
}
I recently created an open source project called swiftui-navigation-stack (https://github.com/biobeats/swiftui-navigation-stack) that contains the NavigationStackView, a view that mimics the navigation behaviours of the standard NavigationView adding some useful features. For example, you could use the NavigationStackView and disable the transition animations as requested by Kontiki in the question. When you create the NavigationStackView just specify .none as transitionType:
struct ContentView : View {
var body: some View {
NavigationStackView(transitionType: .none) {
ZStack {
Color.yellow.edgesIgnoringSafeArea(.all)
PushView(destination: View2()) {
Text("PUSH")
}
}
}
}
}
struct View2: View {
var body: some View {
ZStack {
Color.green.edgesIgnoringSafeArea(.all)
PopView {
Text("POP")
}
}
}
}
PushView and PopView are two views that allow you push and pop views (similar to the SwiftUI NavigationLink). Here is the complete example:
import SwiftUI
import NavigationStack
struct ContentView : View {
var body: some View {
NavigationStackView(transitionType: .none) {
ZStack {
Color.yellow.edgesIgnoringSafeArea(.all)
PushView(destination: View2()) {
Text("PUSH")
}
}
}
}
}
struct View2: View {
var body: some View {
ZStack {
Color.green.edgesIgnoringSafeArea(.all)
PopView {
Text("POP")
}
}
}
}
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView()
}
}
The result is:
It would be great if you guys joined me in improving this open source project.