Why the selected rows become unselected if the list is scrolled (See the pictures)? Xcode 12.2. iOS 14.2.
I also get a console message:
[Assert] Attempted to call -cellForRowAtIndexPath: on the table view
while it was in the process of updating its visible cells, which is
not allowed.
Update
This seems to be iOS 14.2 bug. I downloaded a simulator for iOS 14.1 version and everything works just fine.
import SwiftUI
struct ContentView: View {
#State private var selectedRows = Set<String>()
var items = ["item1", "item2", "item3", "item4","item5","item6","item7","item8","item9","item10","item11","item12","item13","item14","item15","item16","item17","item18","item19","item20","item21","item22"]
var body: some View {
NavigationView {
List(selection: $selectedRows) {
ForEach(items, id: \.self) { item in
Text(item)
}
}
.listStyle(InsetGroupedListStyle())
.environment(\.editMode, Binding.constant(.active))
}
}
}
Related
When trying to navigate back from a view using the environment Dismiss value while also focussing on an empty searchable modifier the view you navigated back to becomes unresponsive. This is due to an empty UIView blocking any interaction with the view as seen in this screenshot:
Empty UIView blocking view after navigating back
This only occurs when the searchbar is focussed and empty when trying to navigate back. When there's a value in the searchbar everything works:
GIF of the bug
Am I doing something wrong here?
Tested on Xcode 14.2 iPhone 14 Pro (iOS 16.0) simulator.
import SwiftUI
struct MainPage: View {
var body: some View {
if #available(iOS 16.0, *) {
NavigationStack {
Text("Main view")
NavigationLink(destination: DetailView()) {
Text("Click me")
}
}
}
}
}
struct DetailView: View {
#Environment(\.dismiss) private var dismiss
#State private var searchText = ""
var body: some View {
VStack {
Text("Detail view")
Button("Go back") {
dismiss()
}
}
.searchable(text: $searchText, placement: .navigationBarDrawer(displayMode: .always))
}
}
This bug only seems to happen when using NavigationStack or NavigationView with a .navigationViewStyle(.stack). When using NavigationView without a navigationViewStyle it seems to work fine. Currently I can work around this using the latter but I would prefer to use NavigationStack as NavigationView has become deprecated since iOS 16.0.
Any help is appreciated.
There are a few posts regarding SwiftUI .inline not resetting to .largeTitle when navigation returns to the parent:
For example:
Navigation bar title stays inline in iOS 15
and
Navigationbar title is inline on pushed view, but was set to large
While earlier posts seem to suggest this has been corrected, I'm running into the same problem, even in iOS 16, but I'm not using a < Back button, instead I'm using "Cancel" (and not show, "Save") on my DestinationView. My goal is to mimic Apple's practice of showing a modal view when adding data, but a show-style push on the navigation stack when viewing and editing existing data (e.g. Contacts app, Reminders app, Calendar app). The brief code below illustrates the problem without adding extra code to handle data updating (e.g. #EnviornmentObject).
When I run this in the Live Preview in Xcode 14.0.1, scheme set to iPhone 13 Pro, no problems. Click a NavLink, return from destination, and ContentView shows .large navigationBarTitle. BUT when I run in the simulator or on a 13 Pro device, returning to Home from a NavigationLink remains .inline unless I pull down on the list. If I switch to iPhone 14 Pro, the live preview looks fine, but the simulator shows a short of abrupt switch from inline back to large, not a smooth animation. Am I doing something wrong in the setup here or is there a bug in the implementation, noting that the behavior oddly holds to .inline on return home to ContentView, if I use this in either a simulator or device for iPhone 13 Pro. Thanks for guidance & insight!
struct ContentView: View {
#State private var sheetIsPresented = false
var items = ["Item1", "Item2", "Item3"]
var body: some View {
NavigationStack {
List {
ForEach(items, id: \.self) { item in
NavigationLink(item, destination: DestinationView(item: item))
.padding()
}
}
.navigationBarTitle("Home", displayMode: .large)
.listStyle(.plain)
.toolbar {
ToolbarItem(placement: .navigationBarTrailing) {
Button {
sheetIsPresented.toggle()
} label: {
Image(systemName: "plus")
}
}
}
}
.sheet(isPresented: $sheetIsPresented) {
NavigationStack {
DestinationView(item: "New!")
}
}
}
}
struct DestinationView: View {
var item: String
#Environment(.dismiss) private var dismiss
var body: some View {
List {
Text(item)
}
.toolbar {
ToolbarItem (placement: .navigationBarLeading) {
Button("Cancel") {
dismiss()
}
}
}
.listStyle(.plain)
.navigationBarTitleDisplayMode(.inline)
.navigationBarBackButtonHidden()
}
}
I have an array of items (numbers) to be presented to the user using NavigationView, List and a leaf page.
When I update an item (numbers[index] = ...) on a leaf page, it updates the list correctly (which I see when I go back to the list), but not the leaf page itself immediately. I see the change if I go back to the list and re-open the same leaf page.
I would like to understand why it does not update the UI immediately, and how to fix it. Here is the simplified code to re-produce this behavior.
ADDITIONAL INFORMATION
This code works fine on Xcode 12. It fails only on Xcode 12.1 (RC1) and Xcode 12.2 (beta3).
import SwiftUI
struct NumberHolder: Identifiable {
let id = UUID()
let value:Int
}
struct Playground: View {
#State var numbers:[NumberHolder] = [
NumberHolder(value:1),
NumberHolder(value:2),
NumberHolder(value:3),
NumberHolder(value:4),
]
var body: some View {
NavigationView {
List(numbers.indices) { index in
let number = numbers[index]
NavigationLink(destination: VStack {
Text("Number: \(number.value)")
Button("Increment") {
numbers[index] = NumberHolder(value: number.value + 1)
}
} ) {
Text("Number: \(number.value)")
}
}
}
}
}
struct Playground_Previews: PreviewProvider {
static var previews: some View {
Playground()
}
}
Update
Apple has since replied to my Issue stating they have resolved this since watchOS 8 beta 3. I've tested this on WatchOS 9 and iOS 16 and this is indeed now working correctly.
Previous answer:
This had me scratching my day for a few weeks.
It appears there are many features within SwiftUI that do not work in Views that are placed in Lists directly, however if you add a ForEach inside the List said features (such as .listRowPlatterColor(.green) on WatchOS) start to work.
Solution
On iOS 14.2 if you wrap the NavigationLink inside a ForEach the NavigationLink destination (leaf page) will update right away when the data model is updated.
So change your code to
var body: some View {
NavigationView {
List {
ForEach(numbers.indices) { index in
let number = numbers[index]
NavigationLink(destination: VStack {
Text("Number: \(number.value)")
Button("Increment") {
numbers[index] = NumberHolder(value: number.value + 1)
}
} ) {
Text("Number: \(number.value)")
}
}
}
}
}
Frustratingly, this does not solve the issue when using WatchOS, in WatchOS 7.0 the leaf page is updated, however in WatchOS 7.1 (version goes hand in hand with iOS 14.2 that suffered this "issue") so I have an issue open with Apple FB8892330
Further frustratingly, I still don't know if this is a bug or a feature in SwiftUI, none of the documentation state the requirement for ForEach inside of Lists
Try this one. I tested and it works.
import SwiftUI
struct NumberHolder: Identifiable {
let id = UUID()
let value:Int
}
struct ContentView: View {
#State var numbers:[NumberHolder] = [
NumberHolder(value:1),
NumberHolder(value:2),
NumberHolder(value:3),
NumberHolder(value:4),
]
var body: some View {
NavigationView {
List(numbers.indices) { index in
NavigationLink(destination: DetailView(numbers: $numbers, index: index)) {
Text("Number: \(self.numbers[index].value)")
}
}
}
}
}
struct DetailView: View {
#Binding var numbers:[NumberHolder]
let index: Int
var body: some View {
VStack {
Text("Number: \(self.numbers[index].value)")
Button("Increment") {
numbers[index] = NumberHolder(value: numbers[index].value + 1)
}
}
}
}
I found the answer. It was a bug in Xcode.
This code (without any changes) works fine under Xcode 12.0, but fails to update under Xcode 12.2 beta 2.
I am having a hard time trying to figured out how to focus on a specific cell/row in the list in the SwiftUI 2.0 and tvOS 14. I need to be able to focus and select a specific record when I am navigated to a view. However when the focus is switched to the list, some random row is focused. I've tried ScrollView and List to create a list of items with Buttons as items and with appropriate prefersDefaultFocus. Nothing works. Here's some sample code:
struct ChannelListView: View {
#Namespace private var namespace
#ObservedObject var viewModel : LiveViewModel
#State var selection = Set<ChannelItem>()
var body: some View {
List(viewModel.channels, selection: $selection){ item in
ScrollViewReader { proxy in
Button(action: {
}){
ChannelItemView(item: item, selectedItem: $viewModel.selectedChannel, onSelected: { id in
})
.padding(.vertical, 2)
}
.buttonStyle(ChannelButtonStyle())
.prefersDefaultFocus(item == viewModel.selectedChannel, in: namespace)
}
}
.focusScope(namespace)
}
}
In my use case, I have to put a TextField below the available items in a List and by using that TextField, we can add items to the List.
Initially, there're no list items (items array is empty)
Here's a minimal, reproducible example
import SwiftUI
struct ContentView: View {
#State var itemName = ""
#State var items = [String]()
var body: some View {
NavigationView {
List {
ForEach(self.items, id: \.self) {
Text($0)
}
VStack {
TextField("Item Name", text: $itemName)
.textFieldStyle(RoundedBorderTextFieldStyle())
Button(action: {
self.items.append(self.itemName)
self.itemName = ""
}) {
Text("Add Item")
}
}
}
.navigationBarTitle(Text("Title"))
}
}
}
We can add a new item to the list by typing something in the TextField and clicking "Add Item" Button , Every item that we add using TextField appears above the TextField in the List. So the TextField goes down in the List (Just like Apple’s Reminders app).
If the app has many items (more than 7 items), the keyboard covers the TextField when the keyboard appears and we can’t see the TextField.
Check this screenshot:
What I want to know is how to automatically scroll the List (move the view up) to see the TextField when keyboard appears (like in Apple's Reminders app).
I had a similar problem in my recent project, the easiest way for me to solve it was to wrap UITextField in SwiftUI and from my custom wrapper reach to the parent scroll view and tell it to scroll when the keyboard appears. I tried my approach on your project and it seems to work.
If you take my code for the wrapper and other files from this GitHub folder: https://github.com/LostMoa/SwiftUI-Code-Examples/tree/master/ScrollTextFieldIntoVisibleRange and then replace the SwiftUI TextField with my custom view (TextFieldWithKeyboardObserver) then it should scroll.
import SwiftUI
struct ContentView: View {
#State var itemName = ""
#State var items = [String]()
var body: some View {
NavigationView {
List {
ForEach(self.items, id: \.self) {
Text($0)
}
VStack {
TextFieldWithKeyboardObserver(text: $itemName, placeholder: "Item Name")
Button(action: {
self.items.append(self.itemName)
self.itemName = ""
}) {
Text("Add Item")
}
}
}
.navigationBarTitle(Text("Title"))
}
}
}
I recently wrote an article explaining this solution: https://lostmoa.com/blog/ScrollTextFieldIntoVisibleRange/