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
Related
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
I'm trying to find the reason why .listRowBackground is not updated when a new item has been added to the list. Here is my code sample:
#main
struct BGtestApp: App {
#ObservedObject var viewModel = ViewModel()
var body: some Scene {
WindowGroup {
ContentView()
.environmentObject(viewModel)
}
}
}
struct ContentView: View {
#EnvironmentObject var vm: ViewModel
var body: some View {
NavigationView {
List {
ForEach(vm.items, id: \.self) { item in
NavigationLink {
DetailView().environmentObject(vm)
} label: {
Text(item)
}
.listRowBackground(Color.yellow)
}
}
}
}
}
struct DetailView: View {
#EnvironmentObject var vm: ViewModel
var body: some View {
Button("Add new") {
vm.items.append("Ananas")
}
}
}
How it looks like:
TIA for you help!
You can force the list to refresh when you cone back to the list. You can tag an id for your list by using .id(). Here is my solution:
struct ContentView: View {
#EnvironmentObject var vm: ViewModel
#State private var viewID = UUID()
var body: some View {
NavigationView {
List {
ForEach(vm.items, id: \.self) { item in
NavigationLink {
DetailView()
.environmentObject(vm)
} label: {
Text(item)
}
}
.listRowBackground(Color.yellow)
}
.id(viewID)
.onAppear {
viewID = UUID()
}
}
}
}
Hope it's helpful for you.
The solution I found is not ideal, but should work. What I did is made items to be #State variable :
struct ContentView: View {
#EnvironmentObject var vm: ViewModel
#State var items: [String] = []
var body: some View {
NavigationView {
VStack {
List {
ForEach(items, id: \.self) { item in
NavigationLink {
DetailView().environmentObject(vm)
} label: {
RowView(item: item)
}
.listRowBackground(Color.yellow)
}
}
.onAppear {
self.items = vm.items
}
}
}
When I press the Move button in the contextMenu, I change the isCopied and setOriginPath variables in the EnvironmentObject. When this change is made, the List view is cleared and I can't see anything on the screen. I don't have any problems when I don't use EnvironmentObject.
ContextMenu:
.contextMenu {
Button {
safeFileVM.hideSelectedFile(fileName: currentFile.fileName)
safeFileVM.takeArrayOfItems()
} label: {
HStack {
Text(!currentFile.isLock ? "Hide" : "Show")
Image(systemName: currentFile.isLock ? "eye" : "eye.slash")
}
}
Button {
safeFileClipboard.setOriginPath = URL(fileURLWithPath: currentFile.localPath)
safeFileClipboard.isCopied = true
} label: {
HStack {
Text("Move")
Image(systemName: "arrow.up.doc")
}
}
}
View:
struct DetailObjectView: View {
#ObservedObject var safeFileVM: SafeFileViewModel = SafeFileViewModel()
#EnvironmentObject var safeFileClipboard: SafeFileClipBoard
var currentFile: MyFile
var currentLocation = ""
var body: some View {
VStack {
.....
}
.contextMenu {
Button {
safeFileVM.hideSelectedFile(fileName: currentFile.fileName)
safeFileVM.takeArrayOfItems()
} label: {
HStack {
Text(!currentFile.isLock ? "Hide" : "Show")
Image(systemName: currentFile.isLock ? "eye" : "eye.slash")
}
}
Button {
safeFileClipboard.setOriginPath = URL(fileURLWithPath: currentFile.localPath)
safeFileClipboard.isCopied = true
} label: {
HStack {
Text("Move")
Image(systemName: "arrow.up.doc")
}
}
}
}
}
In the mini project below, when the EnvironmentObject value changes, navigation goes to the beginning. Why ? How can I fix this ?
Example Project:
Main:
#main
struct EnvironmentTestApp: App {
#StateObject var fooConfig: FooConfig = FooConfig()
var body: some Scene {
WindowGroup {
NavigationView {
ContentView()
.environmentObject(fooConfig)
}
}
}
}
ContentView:
struct ContentView: View {
#EnvironmentObject var fooConfig: FooConfig
private let numbers: [Number] = [.init(item: "1"), .init(item: "2"), .init(item: "3")]
var body: some View {
List {
ForEach(numbers, id: \.id) { item in
DetailView(itemNumber: item.item)
}
}
}
}
struct Number: Identifiable {
var id = UUID()
var item: String
}
DetailView:
struct DetailView: View {
#EnvironmentObject var fooConfig: FooConfig
var itemNumber: String = ""
var body: some View {
NavigationLink(destination: ContentView().environmentObject(fooConfig)) {
Text("\(itemNumber) - \(fooConfig.fooBool == true ? "On" : "Off")")
.environmentObject(fooConfig)
.contextMenu {
Button {
fooConfig.fooBool.toggle()
} label: {
HStack {
Text(fooConfig.fooBool != true ? "On" : "Off")
}
}
}
}
}
}
ObservableObject:
class FooConfig: ObservableObject {
#Published var fooBool: Bool = false
}
Move that from scene into ContentView, because scene is a bad place to update view hierarchy, it is better to do inside view hierarchy, so here
struct EnvironmentTestApp: App {
var body: some Scene {
WindowGroup {
ContentView() // only root view here !!
}
}
}
everything else is inside views, like
struct ContentView: View {
#StateObject private var foo = FooConfig()
var body: some View {
NavigationView {
MainView()
.environmentObject(foo) // << here !!
}
}
}
struct MainView: View {
#EnvironmentObject var fooConfig: FooConfig
private let numbers: [Number] = [.init(item: "1"), .init(item: "2"), .init(item: "3")]
var body: some View {
List {
ForEach(numbers, id: \.id) { item in
DetailView(itemNumber: item.item)
}
}
}
}
and so on...
Tested with Xcode 14 / iOS 16
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()
}
}