My need is simple but I can't seem to figure a way (and many posts are rather complicated or are old/for iOS).
I have a NavigationView with NavigationLink and it all works fine. For certain reasons, I'd like to know the item the user clicked on because it's used for other actions on the view.
I tried putting a button inside the NavigationView but then only the button action fires, but the link doesn't work.
I tried OnTapGesture - then the function fires but isn't propagated so the detail view never shows up.
What am I missing? Is there some way I can do this without overcomplicating?
ForEach(anArray, id: \.self) { entry in
NavigationLink(destination: SettingsView(s: entry)
{
Text("something")
}.onTapGesture {print("Hello")}
}
Here is the solution, actually use a button that does some action and activates a link
Tested with Xcode 11.5b2
#State private var activatedLink: Int? = nil
// ... other code
ForEach(Array(anArray.enumerated()), id: \.element) { (i, entry) in
Button("something") {
print(">> some action")
self.activatedLink = i // << order might be important !!
}.background(
NavigationLink(destination: SettingsView(s: entry), tag: i, selection: $activatedLink) { EmptyView() }
.buttonStyle(PlainButtonStyle()) // << required !!
)
}
Related
Goal: have a SwiftUI architecture where the "add new item" and "edit existing item" are solved by the same view (EditItemView). However, for some reason, when I do this, the runtime agent complains of "Modifying state during view update, this will cause undefined behavior".
This is the code I want to use, which ensures that the EDITING of the item and ADDING a new item are handled by the same EditItemView:
var body: some View {
NavigationView
{
ScrollView
{
LazyVGrid(columns: my_columns)
{
ForEach(items, id: \.id)
{
let item = $0
// THIS LINE TO EDIT AN EXISTING ITEM
NavigationLink(destination: EditItemView(item: item))
{
ItemView(item: item)
}
}
}
}
.navigationBarItems(trailing:
// THIS LINE TO ADD A NEW ITEM:
NavigationLink(destination: EditItemView(item: Data.singleton.createItem(name: "New item", value: 5.0))
{
Image(systemName: "plus")
}
)
}
}
It doesn't work, leading to the issue highlighted above. I am forced to separate the functionality for Edit and Add into two distinct Views, which then works:
var body: some View {
NavigationView
{
ScrollView
{
LazyVGrid(columns: my_columns)
{
ForEach(items, id: \.id)
{
let item = $0
// THIS LINE TO EDIT AN EXISTING ITEM
NavigationLink(destination: EditItemView(item: item))
{
ItemView(item: item)
}
}
}
}
.sheet(isPresented: $isPresented)
{
// FORCED TO USE SEPARATE VIEW
AddItemView { name, value in
_ = Data.singleton.createItem(name: name, value: value)
self.isPresented = false
}
}
.navigationBarItems(trailing: Button(action: { self.isPresented.toggle()}) { Image(systemName: "plus")})
}
}
I don't understand why the code in the first version is considered to modify the state while updating view, because to me, it's sequential: new Item is created and THEN a view is shown for that Item.
Any ideas?
The destination of NavigationLink is not rendered lazily, meaning it'll get rendered when the NavigationLink itself is rendered -- not when clicked through.
The sheet code, depending on platform and SwiftUI version, may have the same issue, but apparently does not in the version you're using. Or, the closure you provide to AddItemView isn't run immediately -- since you didn't include the code, it's not clear.
To solve the issue in the first method, you can use the following SO answer which provides a lazy NavigationLink: https://stackoverflow.com/a/61234030/560942
I am quite new to swiftUI. I have created a grid view on tapping on which I want to go to next screen. But somehow I am not able to manage to push to next screen. I am doing like this:
var body: some View {
NavigationView {
ScrollView {
LazyVGrid(columns: gridItems, spacing: 16) {
ForEach(viewModel.pokemon) { pokemon in
PokemonCell(pokemon: pokemon, viewModel: viewModel)
.onTapGesture {
NavigationLink(destination: PokemonDetailView(pokemon: pokemon)) {
Text(pokemon.name)
}
}
}
}
}
.navigationTitle("Pokedex")
}
}
Upon doing like this, I am getting a warning stating
Result of 'NavigationLink<Label, Destination>' initializer is unused
Can someone please guide me, how to do this?
.onTapGesture adds an action to perform when the view recognizes a tap gesture. In your case you don't need to use .onTapGesture. If you want to go to another view when cell is tapped you need to write NavigationLink as below.
NavigationLink(destination: PokemonDetailView(pokemon: pokemon)) {
PokemonCell(pokemon: pokemon, viewModel: viewModel)
}
If you want to use .onTapGesture, another approach is creating #State for your tapped cell's pokemon and using NavigationLink's isActive binding. So when user tap the cell it will change the #State and toggle the isActive in .onTapGesture. You may need to add another Stack (ZStack etc.) for this.
NavigationView {
ZStack {
NavigationLink("", destination: PokemonDetailView(pokemon: pokemon), isActive: $isNavigationActive).hidden()
ScrollView {
// ...
How do I respond to focus events on tvOS in SwiftUI?
I have the following SwiftUI view:
struct MyView: View {
var body: some View {
VStack {
Button(action: {
print("Button 1 pressed")
}) {
Text("Button 1")
}.focusable(true) { focused in
print("Button 1 focused: \(focused)")
}
Button(action: {
print("Button 2 pressed")
}) {
Text("Button 2")
}.focusable(true) { focused in
print("Button 2 focused: \(focused)")
}
}
}
Clicking either of the buttons prints out correctly. However, changing focus between the two buttons does not print anything.
This guy is doing the same thing with rows in a list & says it started working for him with the Xcode 11 GM, but I'm on 11.5 and it's definitely not working (at least not for Buttons (or Toggles - I tried those too)).
Reading the documentation, this appears to be the correct way to go about this, but it doesn't seem to actually work. Am I missing something, or is this just broken?
In case anybody else stumbles upon this question, the answer is to make your view data-focused
So, if you have a list of movies in a scrollview, you would add this to your outer view:
var myMovieList: [Movie];
#FocusState var selectedMovie: Int?;
And then somewhere in your body property:
ForEach(0..<myMovieList.count) { index in
MovieCard(myMovieList[i])
.focusable(true)
.focused($selectedMovie, equals: index)
}
.focusable() tells the OS that this element is focusable, and .focused tells it to make that view focused when the binding variable ($selected) equals the value passed to equals: ...
For example on tvOS, if you wrap this in a scrollview and press left/right, it will change the selection and update the selected index in the $selectedMovie variable; you can then use that to index into your movie list to display extra info.
Here is a more complete example that will also scale the selected view:
https://pastebin.com/jejwYxMU
I am playing around with SwiftUI, and am currently building a Form using a Picker.
import SwiftUI
struct ContentView: View {
private let names = ["Bill", "Peter", "Johan", "Kevin"]
#State private var favoritePerson = "Bill"
var body: some View {
NavigationView {
Form {
Picker("Favorite person", selection: $favoritePerson) {
ForEach(names, id: \.self) { name in
Text(name)
}
}
}
.navigationBarTitle("Form", displayMode: .inline)
}
}
}
The first time you tap on the "Favorite person" row, the picker shows up fine, and tapping on one of the names brings you back to the form. But tapping on the form row a second time doesn't do anything: you don't go to the picker, the row stays highlighted but nothing happens. If this is a SwiftUI bug, is there a known workaround? (I already needed to use a small navigation bar title to work around the Picker UI bug where otherwise its content moves up when it's shown ☹️)
this issue is just one with the simulator. If you build the app on a physical iOS device, it no longer becomes an issue. It's like that bug with Navigation Link that would only work once.
I have the same problem in Xcode 11.4 and also in the real device.
Picker change didn't call CreateTab, it only worked in initialize.
Picker("Numbers", selection: $selectorIndex) {
ForEach(0 ..< formData.tabs.count) { index in
Text(formData.tabs[index].name).tag(index)
}
}
.pickerStyle(SegmentedPickerStyle())
.onReceive([self.selectorIndex].publisher.first()) { (value) in
print(value)
CreateTab(tabs: formData.tabs, index: self.selectorIndex)
}
Using SwiftUI, I would like to have the ability to change the button on my NavigationView based upon some Bool value indicating if it should be On or Off.
This would behave similar to how with UIKit you can replace a bar button item on either side of the screen to show a different button & associated action upon clicking.
I am able to get it working with the following code, but I am not certain if this is the best way to accomplish it, so am open to improvement.
import SwiftUI
struct HomeList: View {
#State var isOn = true
var body: some View {
NavigationView {
List(1 ..< 4) { index in
Text("Row \(index)")
}
.navigationBarTitle(Text(verbatim: "Title"), displayMode: .inline)
.navigationBarItems(trailing:
Button(action: {
self.isOn = !self.isOn
}, label: {
Text(self.isOn ? "On" : "Off")
})
)
}
}
}
The key pieces being:
Using the #State modifier on my isOn variable, which tells my interface to invalidate & re-render upon changes
Having my Button action modify isOn &it can also support other actions if I need
The ternary operator in my Button label that updates the Text (or an Image if I want) to reflect the correct appearance
Finally, how it appears in action: