I wanted to show a list of tags that can be selectable and want to make sure only one tag is selected in the list.
I tried to use #State, #ObservedObject, and #Published, but no luck. What is the best solution here?
import SwiftUI
struct Tag: Identifiable {
let id: Int
let name: String
var selected: Bool = false
}
struct ContentView: View {
#State var tags: [Tag]
var body: some View {
VStack {
ForEach(tags) { tag in
TagView(name: tag.name, isSelected: tag.selected) {
for (index, _) in tags.enumerated() {
// select only one tag
tags[index].selected = tags[index].id == tag.id
}
}
}
}
}
}
struct TagView: View {
let name: String
#State var isSelected: Bool
var onAction: (() -> Void) = { }
var body: some View {
Button(action: onAction) {
Text(name)
.foregroundColor(.white)
.padding()
.background(
isSelected ? Color.red : Color.blue
)
}
}
}
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView(tags: [
Tag(id: 1, name: "Swift"),
Tag(id: 2, name: "Xcode"),
Tag(id: 3, name: "Apple")
])
}
}
Removing #State of isSelected variable in TagView resolved the issue
Related
I'm trying to build out a simple navigation where you can click on items in a link and pop back to the root controller from a sheet view. As you can see from the video below, when I tap on an item in the list, the wrong item is loaded (there's an offset between the row I click and the one that gets highlighted and loaded).
I also get the error SwiftUI encountered an issue when pushing aNavigationLink. Please file a bug.
Here's all my code:
import SwiftUI
struct ContentView: View {
#State var rootIsActive:Bool = false
var body: some View {
NavigationView{
AllProjectView(rootIsActive: self.rootIsActive)
}
.navigationBarTitle("Root")
.navigationViewStyle(StackNavigationViewStyle())
.environment(\.rootPresentationMode, self.$rootIsActive)
}
}
struct AllProjectView: View {
#State var rootIsActive:Bool = false
#State var projects: [String] = ["1", "2", "3"]
var body: some View{
List{
ForEach(projects.indices, id: \.self){ idx in
ProjectItem(name: self.$projects[idx], rootIsActive: self.$rootIsActive)
}
}.navigationBarTitle("All Projects")
}
}
struct ProjectItem: View{
#Binding var name: String
#Binding var rootIsActive: Bool
init(name: Binding<String>, rootIsActive: Binding<Bool>){
self._name = name
self._rootIsActive = rootIsActive
}
var body: some View{
NavigationLink(
destination: ProjectView(name: self.name),
isActive: self.$rootIsActive){
Text(name)
}
.isDetailLink(false)
.padding()
}
}
struct ProjectView: View {
var name: String
#State var isShowingSheet: Bool = false
#Environment(\.presentationMode) private var presentationMode: Binding<PresentationMode>
#Environment(\.rootPresentationMode) private var rootPresentationMode: Binding<RootPresentationMode>
var body: some View{
VStack{
Text(name)
Button("Show Sheet"){
self.isShowingSheet = true
}
}
.sheet(isPresented: $isShowingSheet){
Button("return to root"){
self.isShowingSheet = false
print("pop view")
self.presentationMode.wrappedValue.dismiss()
print("pop root")
self.rootPresentationMode.wrappedValue.dismiss()
}
}
.navigationBarTitle("Project View")
}
}
// from https://stackoverflow.com/a/61926030/1720985
struct RootPresentationModeKey: EnvironmentKey {
static let defaultValue: Binding<RootPresentationMode> = .constant(RootPresentationMode())
}
extension EnvironmentValues {
var rootPresentationMode: Binding<RootPresentationMode> {
get { return self[RootPresentationModeKey.self] }
set { self[RootPresentationModeKey.self] = newValue }
}
}
typealias RootPresentationMode = Bool
extension RootPresentationMode {
public mutating func dismiss() {
self.toggle()
}
}
You only have one isRootActive variable that you're using. And, it's getting repeated for each item on the list. So, as soon as any item on the list is tapped, the isActive property for each NavigationLink turns to true.
Beyond that, your isRootActive isn't actually doing anything right now, since your "Return to root" button already does this:
self.isShowingSheet = false
self.presentationMode.wrappedValue.dismiss()
At that point, there's nothing more to dismiss -- it's already back at the root view.
My removing all of the root and isActive stuff, you get this:
struct ContentView: View {
var body: some View {
NavigationView{
AllProjectView()
}
.navigationBarTitle("Root")
.navigationViewStyle(StackNavigationViewStyle())
}
}
struct AllProjectView: View {
#State var projects: [String] = ["1", "2", "3"]
var body: some View{
List{
ForEach(projects.indices, id: \.self){ idx in
ProjectItem(name: self.$projects[idx])
}
}.navigationBarTitle("All Projects")
}
}
struct ProjectItem: View{
#Binding var name: String
var body: some View{
NavigationLink(
destination: ProjectView(name: self.name)
){
Text(name)
}
.isDetailLink(false)
.padding()
}
}
struct ProjectView: View {
var name: String
#State var isShowingSheet: Bool = false
#Environment(\.presentationMode) private var presentationMode: Binding<PresentationMode>
var body: some View{
VStack{
Text(name)
Button("Show Sheet"){
self.isShowingSheet = true
}
}
.sheet(isPresented: $isShowingSheet){
Button("return to root"){
self.isShowingSheet = false
print("pop view")
self.presentationMode.wrappedValue.dismiss()
}
}
.navigationBarTitle("Project View")
}
}
If you had an additional view in the stack, you would need a way to keep track of if the root were active. I've used a custom binding here that converts an optional String representing the project's name to a Bool value that gets passed down the view hierarchy:
struct ContentView: View {
var body: some View {
NavigationView{
AllProjectView()
}
.navigationBarTitle("Root")
.navigationViewStyle(StackNavigationViewStyle())
}
}
struct AllProjectView: View {
#State var projects: [String] = ["1", "2", "3"]
#State var activeProject : String?
func activeBindingForProject(name : String) -> Binding<Bool> {
.init {
name == activeProject
} set: { newValue in
activeProject = newValue ? name : nil
}
}
var body: some View{
List{
ForEach(projects.indices, id: \.self){ idx in
InterimProjectView(name: self.$projects[idx],
isActive: activeBindingForProject(name: self.projects[idx]))
}
}.navigationBarTitle("All Projects")
}
}
struct InterimProjectView: View {
#Binding var name : String
#Binding var isActive : Bool
var body : some View {
NavigationLink(destination: ProjectItem(name: $name, isActive: $isActive),
isActive: $isActive) {
Text("Next : \(isActive ? "true" : "false")")
}
}
}
struct ProjectItem: View {
#Binding var name: String
#Binding var isActive: Bool
var body: some View{
NavigationLink(
destination: ProjectView(name: self.name, isActive: $isActive)
){
Text(name)
}
.isDetailLink(false)
.padding()
}
}
struct ProjectView: View {
var name: String
#Binding var isActive : Bool
#State var isShowingSheet: Bool = false
var body: some View{
VStack{
Text(name)
Button("Show Sheet"){
self.isShowingSheet = true
}
}
.sheet(isPresented: $isShowingSheet){
Button("return to root"){
self.isShowingSheet = false
print("pop root")
self.isActive.toggle()
}
}
.navigationBarTitle("Project View")
}
}
Using a data-structure for isActive bools for dynamic NavigationLinks to enable a programmatic pop-back doesn't work. Tapping the Pop Back in the Destination should pop the view back to the root DynamicList, but it doesn't work.
import SwiftUI
struct DynamicList: View {
#ObservedObject var listViewModel = ListViewModel()
var body: some View {
NavigationView {
List {
ForEach(0..<self.listViewModel.cities.count, id: \.self) { index in
NavigationLink(
destination: Destination(isActive: $listViewModel.isActiveItems[index], city: $listViewModel.cities[index]),
isActive: $listViewModel.isActiveItems[index],
label: {
Text(listViewModel.cities[index])
})
}
}
.navigationBarTitle(Text("Locations"))
.navigationBarItems(trailing: Button(action: {
self.addRow()
}) {
Image(systemName: "plus")
})
}
}
private func addRow() {
self.listViewModel.addCity(city: ["New York", "London", "Moskau", "Sydney"].randomElement() ?? "")
}
}
class ListViewModel: ObservableObject {
#Published var cities: [String] = []
#Published var isActiveItems: [Bool] = []
func addCity(city: String){
cities.append(city)
isActiveItems.append(false)
}
}
struct Destination: View {
#Binding var isActive: Bool
#Binding var city: String
var body: some View {
Text(city)
Button(action: {
isActive.toggle()
}, label: {
Text("Pop Back")
})
}
}
struct DynamicList_Previews: PreviewProvider {
static var previews: some View {
DynamicList()
}
}
i am sure i am making something wrong, but i don't know what.
I have a small list and i update texts with a timer which i can see in the debugger which updates. But the list won't be updated...
Thank you for help.
struct ListTest: View {
#State var texts : [String]
var body: some View {
List {
ForEach(self.texts, id: \.self) { text in
Text(text)
}
}
}
}
struct ContentView: View {
#State var texts = ["a"]
var body: some View {
ListTest(texts: self.texts)
.onAppear() {
Timer.scheduledTimer(withTimeInterval: 0.5, repeats: true) { (timer) in
self.texts.append("\(self.texts.count)")
print(self.texts)
}
}
}
}
remove #State property wrapper from your ListTest
struct ListTest: View {
var texts : [String]
var body: some View {
List {
ForEach(self.texts, id: \.self) { text in
Text(text)
}
}
}
}
Finally, think about more "combine compatible" code
import SwiftUI
struct ListTest: View {
var texts: [String]
var body: some View {
List {
ForEach(self.texts, id: \.self) { text in
Text(text)
}
}
}
}
struct ContentView: View {
#State var texts = ["a"]
let tp = Timer.publish(every: 0.5, on: .main, in: .default).autoconnect()
var body: some View {
ListTest(texts: self.texts)
.onReceive(tp) { (date) in
self.texts.append("\(self.texts.count)")
}
}
}
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView()
}
}
which is functionally equal
The code for the basic app from Anlil's answer works fine. If I edit the datamodel to be more like mine, with a multidimensional String array, I get something like:
import SwiftUI
import Combine
struct ContentView: View {
#EnvironmentObject var dm: DataManager
var body: some View {
NavigationView {
List {
NavigationLink(destination:AddView().environmentObject(self.dm)) {
Image(systemName: "plus.circle.fill").font(.system(size: 30))
}
ForEach(dm.array, id: \.self) { item in
NavigationLink(destination: DetailView(item: item)) {
Text(item[0])
}
}
}
}
}
}
struct DetailView: View {
var item : [String] = ["", "", ""]
var body: some View {
VStack {
Text(item[0])
Text(item[1])
Text(item[2])
}
}
}
struct AddView: View {
#EnvironmentObject var dm: DataManager
#State var item0 : String = "" // needed by TextField
#State var item1 : String = "" // needed by TextField
#State var item2 : String = "" // needed by TextField
#State var item : [String] = ["", "", ""]
var body: some View {
VStack {
TextField("Write something", text: $item0)
.textFieldStyle(.roundedBorder)
.padding(.horizontal)
TextField("Write something", text: $item1)
.textFieldStyle(.roundedBorder)
.padding(.horizontal)
TextField("Write something", text: $item2)
.textFieldStyle(.roundedBorder)
.padding(.horizontal)
Button(action: {
self.item = [self.item0, self.item1, self.item2]
print(self.item)
self.dm.array.append(self.item)
}) {
Text("Save")
}
}
}
}
class DataManager: BindableObject {
var willChange = PassthroughSubject<Void, Never>()
var array : [[String]] = [["Item 1","Item 2","Item 3"],["Item 4","Item 5","Item 6"],["Item 7","Item 8","Item 9"]] {
didSet {
willChange.send()
}
}
}
There are no errors and the code runs as expected. Before I'm going to rewrite my own code (with the lessons I've learned solar) it would be nice if the code could be checked.
I'm really impressed with SwiftUI!
If your "source of truth" is an array of some "model instances", and you just need to read values, you can pass those instance around like before:
import SwiftUI
import Combine
struct ContentView: View {
#EnvironmentObject var dm: DataManager
var body: some View {
NavigationView {
List(dm.array, id: \.self) { item in
NavigationLink(destination: DetailView(item: item)) {
Text(item)
}
}
}
}
}
struct DetailView: View {
var item : String
var body: some View {
Text(item)
}
}
class DataManager: BindableObject {
var willChange = PassthroughSubject<Void, Never>()
let array = ["Item 1", "Item 2", "Item 3"]
}
#if DEBUG
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView().environmentObject(DataManager())
}
}
#endif
You need to pass the EnvironmentObject only if some views are able to manipulate the data inside the instances... in this case you can easily update the EnvironmentObject's status and everything will auto-magically updated everywhere!
The code below shows a basic App with "list", "detail" and "add", so you can see 'environment' in action (the only caveat is that you have to manually tap < Back after tapped the Save button). Try it and you'll see the list that will magically update.
import SwiftUI
import Combine
struct ContentView: View {
#EnvironmentObject var dm: DataManager
var body: some View {
NavigationView {
List {
NavigationLink(destination:AddView().environmentObject(self.dm)) {
Image(systemName: "plus.circle.fill").font(.system(size: 30))
}
ForEach(dm.array, id: \.self) { item in
NavigationLink(destination: DetailView(item: item)) {
Text(item)
}
}
}
}
}
}
struct DetailView: View {
var item : String
var body: some View {
Text(item)
}
}
struct AddView: View {
#EnvironmentObject var dm: DataManager
#State var item : String = "" // needed by TextField
var body: some View {
VStack {
TextField("Write something", text: $item)
.textFieldStyle(.roundedBorder)
.padding(.horizontal)
Button(action: {
self.dm.array.append(self.item)
}) {
Text("Save")
}
}
}
}
class DataManager: BindableObject {
var willChange = PassthroughSubject<Void, Never>()
var array : [String] = ["Item 1", "Item 2", "Item 3"] {
didSet {
willChange.send()
}
}
}
#if DEBUG
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView().environmentObject(DataManager())
}
}
#endif
This looks like a very simple thing, but I can't figure out how to do this:
I have a List embedded in a NavigationView, containing a NavigationLink to view the detail of the item.
I have a save bar button where I would like to save the selected item. But how can I access the selected item?
It isn't visible in the button's action closure.
struct ItemList : View {
#EnvironmentObject var items: ItemsModel
var body: some View {
NavigationView {
List(items) { item in
NavigationLink(destination: ItemDetail(item: item)) {
Text(item.name)
}
}
.navigationBarTitle(Text("Item"))
.navigationBarItems(trailing: Button(action: {
self.save(/*item: item */) // How can I access item here?
}, label: {
Text("Save")
}))
}
}
func save(item: Item) {
print("Saving...")
}
}
Navigation links are not obligatory to accomplish this.
import SwiftUI
struct ContentView: View {
struct Ocean: Identifiable, Hashable {
let name: String
var id: Self { self }
}
private var oceans = [
Ocean(name: "Pacific"),
Ocean(name: "Atlantic"),
Ocean(name: "Indian"),
Ocean(name: "Southern"),
Ocean(name: "Arctic")
]
#State private var selectedOceans = [Ocean]()
#State private var multiSelection = Set<Ocean.ID>()
var body: some View {
VStack {
Text("Oceans")
List(oceans, selection: $multiSelection) {
Text($0.name)
}
.navigationTitle("Oceans")
.environment(\.editMode, .constant(.active))
.onTapGesture {
// Walkaround: try how it works without `asyncAfter()`
DispatchQueue.main.asyncAfter(deadline: .now() + 0.05, execute: {
selectedOceans = Array(multiSelection)
print(selectedOceans)
})
}
Divider()
Text("Selected oceans")
List(selectedOceans, selection: $multiSelection) {
Text($0.name)
}
}
Text("\(multiSelection.count) selections")
}
}
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView()
}
}