SwiftUI Programmatically Select List Item - ios

I have a SwiftUI app with a basic List/Detail structure. A new item is created from
a modal sheet. When I create a new item and save it I want THAT list item to be
selected. As it is, if no item is selected before an add, no item is selected after
an add. If an item is selected before an add, that same item is selected after the
add.
I'll include code for the ContentView, but this is really the simplest example of
List/Detail.
struct ContentView: View {
#ObservedObject var resortStore = ResortStore()
#State private var addNewResort = false
#State private var coverDeletedDetail = false
#Environment(\.presentationMode) var presentationMode
var body: some View {
List {
ForEach(resortStore.resorts) { resort in
NavigationLink(destination: ResortView(resort: resort)) {
HStack(spacing: 20) {
Image("FlatheadLake1")
//bunch of modifiers
VStack(alignment: .leading, spacing: 10) {
//the cell contents
}
}
}
}
.onDelete { indexSet in
self.removeItems(at: [indexSet.first!])
self.coverDeletedDetail.toggle()
}
if UIDevice.current.userInterfaceIdiom == .pad {
NavigationLink(destination: WelcomeView(), isActive: self.$coverDeletedDetail) {
Text("")
}
}
}//list
.onAppear(perform: self.selectARow)
.navigationBarTitle("Resorts")
.navigationBarItems(leading:
//buttons
}//body
func removeItems(at offsets: IndexSet) {
resortStore.resorts.remove(atOffsets: offsets)
}
func selectARow() {
//nothing that I have tried works here
print("selectARow")
}
}//struct
And again - the add item modal is extremely basic:
struct AddNewResort: View {
//bunch of properties
var body: some View {
VStack {
Text("Add a Resort")
VStack {
TextField("Enter a name", text: $resortName)
//the rest of the fields
}
.textFieldStyle(RoundedBorderTextFieldStyle())
.padding(EdgeInsets(top: 20, leading: 30, bottom: 20, trailing: 30))
Button(action: {
let newResort = Resort(id: UUID(), name: self.resortName, country: self.resortCountry, description: self.resortDescription, imageCredit: "Credit", price: Int(self.resortPriceString) ?? 0, size: Int(self.resortSizeString) ?? 0, snowDepth: 20, elevation: 3000, runs: 40, facilities: ["bar", "garage"])
self.resortStore.resorts.append(newResort)
self.presentationMode.wrappedValue.dismiss()
}) {
Text("Save Trip")
}
.padding(.trailing, 20)
}
}
}
To show the issue - The list with a selection:
The list after a new item created showing the previous selection:
Any guidance would be appreciated. Xcode 11.4

I tried to reconstitute your code as closely as could so that it builds. Here is what I have in the end. We have a list of resorts and when a new resort is saved in the AddNewResort sheet, if we are currently in split view (horizontalSizeClass is regular), we will select the new resort, otherwise just dismiss the sheet.
import SwiftUI
class ResortStore: ObservableObject {
#Published var resorts = [Resort(id: UUID(), name: "Resort 1")]
}
struct ContentView: View {
#ObservedObject var resortStore = ResortStore()
#State private var addingNewResort = false
#State var selectedResortId: UUID? = nil
var navigationLink: NavigationLink<EmptyView, ResortView>? {
guard let selectedResortId = selectedResortId,
let selectedResort = resortStore.resorts.first(where: {$0.id == selectedResortId}) else {
return nil
}
return NavigationLink(
destination: ResortView(resort: selectedResort),
tag: selectedResortId,
selection: $selectedResortId
) {
EmptyView()
}
}
var body: some View {
NavigationView {
ZStack {
navigationLink
List {
ForEach(resortStore.resorts, id: \.self.id) { resort in
Button(action: {
self.selectedResortId = resort.id
}) {
Text(resort.name)
}
.listRowBackground(self.selectedResortId == resort.id ? Color.gray : Color(UIColor.systemBackground))
}
}
}
.navigationBarTitle("Resorts")
.navigationBarItems(trailing: Button("Add Resort") {
self.addingNewResort = true
})
.sheet(isPresented: $addingNewResort) {
AddNewResort(selectedResortId: self.$selectedResortId)
.environmentObject(self.resortStore)
}
WelcomeView()
}
}
}
struct ResortView: View {
let resort: Resort
var body: some View {
Text("Resort View for resort name: \(resort.name).")
}
}
struct AddNewResort: View {
//bunch of properties
#Binding var selectedResortId: UUID?
#State var resortName = ""
#Environment(\.presentationMode) var presentationMode
#Environment(\.horizontalSizeClass) var horizontalSizeClass
#EnvironmentObject var resortStore: ResortStore
var body: some View {
VStack {
Text("Add a Resort")
VStack {
TextField("Enter a name", text: $resortName)
//the rest of the fields
}
.textFieldStyle(RoundedBorderTextFieldStyle())
.padding(EdgeInsets(top: 20, leading: 30, bottom: 20, trailing: 30))
Button(action: {
let newResort = Resort(id: UUID(), name: self.resortName)
self.resortStore.resorts.append(newResort)
self.presentationMode.wrappedValue.dismiss()
if self.horizontalSizeClass == .regular {
self.selectedResortId = newResort.id
}
}) {
Text("Save Trip")
}
.padding(.trailing, 20)
}
}
}
struct WelcomeView: View {
var body: some View {
Text("Welcome View")
}
}
struct Resort {
var id: UUID
var name: String
}
We need to keep track of the selectedResortId
We create an invisible NavigationLink that will programmatically navigate to the selected resort
We make our list row a Button, so that the user can select a resort by tapping on the row
I started writing a series of articles about navigation in SwiftUI List view, there are a lot of points to consider while implementing programmatic navigation.
Here is the one that describes this solution that I'm suggesting: SwiftUI Navigation in List View: Programmatic Navigation. This solution works at the moment on iOS 13.4.1. SwiftUI is changing rapidly, so we have to keep on checking.
And here is my previous article that explains why a more simple solution of adding a NavigationLink to each List row has some problems at the moment SwiftUI Navigation in List View: Exploring Available Options
Let me know if you have questions, I'd be happy to help where I can.

Related

SwiftUI Bizarre Picker Behavior with Modal Sheets

I'm experiencing a truly bizarre behavior with an app that has pickers in a view that
calls a map as a sheet modal. The pickers are not directly involved in calling the map -
but set conditions for the annotations that will be displayed. And in the simple example
I have included below, it is clear the issue has nothing to do with the map - the
problem behavior is present with a simple text view in the modal.
The issue: if the user swipes to dismiss the modal it appears to always work as expected.
If the user taps a button to dismiss the modal with either the environment dismiss or
through a binding to the #State that calls the view, then after the second showing of the
modal, you can no longer raise the picker - the displayed value just turns color - as if
a color toggle on tap. I've also tried showing the modal as full screen, as an animation
and as a transition. I get the same result every time. I'm at the point where I think this
must be an Xcode bug, but I hope someone can show me a solution. The same behavior exists
in Preview, Simulator and a real Device.
Here is a very stripped down example which demonstrates the issue:
enum StorageKeys: String {
case appChosenFuel, appChosenState
}//enum
struct ContentView: View {
#State private var showGroupMapView: Bool = false
#State private var showTooBigAlert: Bool = false
#State private var justANumber: Int = 500
var body: some View {
NavigationView {
VStack {
Text("Picker plus Sheet Test")
.padding()
FuelPickerView()
}
.toolbar {
ToolbarItemGroup(placement: .navigationBarTrailing) {
Button {
if justANumber > 1000 {
showTooBigAlert = true
} else {
withAnimation {
showGroupMapView.toggle()
}
}
} label: {
Image(systemName: "map")
.font(.system(size: 20))
.frame(width: 40, height: 40)
}
.sheet(isPresented: $showGroupMapView, onDismiss: {
print("you dismissed me")
}) {
GroupMapView()
}
}//toolbar group
}//toolbar
}//nav
}//body
}//sruct
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView()
}
}
struct GroupMapView: View {
#Environment(\.presentationMode) var presentationMode
var body: some View {
ZStack {
Text("This is the map view")
VStack {
HStack {
Spacer()
Button {
presentationMode.wrappedValue.dismiss()
} label: {
Image(systemName: "gear")
.padding(.trailing, 20)
.padding(.top, 20)
}
}
Spacer()
}
}//z
}
}//struct
class FuelPickerViewModel: ObservableObject {
struct FuelItem: Identifiable, Hashable {
let id = UUID()
let name: String
let initials: String
}
#Published var fuelItems = [
FuelItem(name: "Biodiesel (B20 and above)", initials: "BD"),
FuelItem(name: "Compressed Natural Gas", initials: "CNG"),
FuelItem(name: "Ethanol (E85)", initials: "E85"),
FuelItem(name: "Electric", initials: "ELEC"),
FuelItem(name: "Hydrogen", initials: "HY"),
FuelItem(name: "Liquified Natural Gas", initials: "LNG"),
FuelItem(name: "Liquified Petroleum Gas (Propane)", initials: "LPG")
]
}//class
struct FuelPickerView: View {
#AppStorage(StorageKeys.appChosenFuel.rawValue) var appChosenFuel = "ELEC"
#AppStorage(StorageKeys.appChosenState.rawValue) var appChosenState = "CO"
#StateObject var fuelPickerVM = FuelPickerViewModel()
var body: some View {
return VStack {
Picker("Fuel", selection: $appChosenFuel) {
ForEach(fuelPickerVM.fuelItems, id: \.self) {
Text($0.initials)
}
}
}
}//body
}//struct
And after the second modal display/dismiss with the button, tapping the picker does
nothing except change the background color:
Any guidance would be appreciated: Xcode 13.2.1 iOS 15.2

SwiftUI - View disappears if animated

I am building a custom segmented control. This is the code that I have written.
struct SegmentedControl: View {
private var items: [String] = ["One", "Two", "Three"]
#Namespace var animation:Namespace.ID
#State var selected: String = "One"
var body: some View {
ScrollView(.horizontal) {
HStack {
ForEach(items, id: \.self) { item in
Button(action: {
withAnimation(.spring()){
self.selected = item
}
}) {
Text(item)
.font(Font.subheadline.weight(.medium))
.foregroundColor(selected == item ? .white : .accentColor)
.padding(.horizontal, 25)
.padding(.vertical, 10)
.background(zStack(item: item))
}
}
} .padding()
}
}
private func zStack(item: String) -> some View {
ZStack{
if selected == item {
Color.accentColor
.clipShape(Capsule())
.matchedGeometryEffect(id: "Tab", in: animation)
} else {
Color(.gray)
.clipShape(Capsule())
}}
}
}
A control is Blue when it is selected.
It works as expected most of the time like in the following GIF.
However, sometimes if you navigate back and forth very fast, the Color.accentColor moves off screen and disappears as you see in the following GIF. I have used a lot of time but could not fix it.
Sometimes, I get this error.
Multiple inserted views in matched geometry group Pair<String,
ID>(first: "Tab", second: SwiftUI.Namespace.ID(id: 248)) have `isSource:
true`, results are undefined.
Info, It is easier to test it on a physical device rather than a simulator.
Update
This is my all codde including the ContentView and the Modal.
struct ContentView: View {
#State private var isPresented: Bool = false
var body: some View {
NavigationView {
VStack {
Button(action: {
self.isPresented.toggle()
}, label: {
Text("Button")
})
}
}
.sheet(isPresented: $isPresented, content: {
ModalView()
})
}
}
struct ModalView: View {
var body: some View {
NavigationView {
NavigationLink(
destination: TabbarView(),
label: {
Text("Navigate")
})
}
}
}
struct TabbarView: View {
private var items: [String] = ["One", "Two", "Three"]
#Namespace var animation:Namespace.ID
#State var selected: String = "" // change here
var body: some View {
ScrollView(.horizontal) {
HStack {
ForEach(items, id: \.self) { item in
Button(action: {
withAnimation{
self.selected = item
}
}) {
Text(item)
.font(Font.subheadline.weight(.medium))
.foregroundColor(selected == item ? .white : .accentColor)
.padding(.horizontal, 25)
.padding(.vertical, 10)
.background(zStack(item: item))
}
}
} .padding()
}
.onAppear { self.selected = "One" } // add this
}
private func zStack(item: String) -> some View {
ZStack{
if selected == item {
Color.accentColor
.clipShape(Capsule())
.matchedGeometryEffect(id: "Tab", in: animation)
} else {
Color(.gray)
.clipShape(Capsule())
}}
}
}

SwiftUI setting individual backgrounds for list Elements that fill the element

So I'm trying to make a list where the background of each element is an image that completely fills the element and I'm struggling to get it to completely fill the area.
here's some simple example code showing what I have so far.
struct Event {
var description:String = "description"
var title:String = "Title"
var view:Image
}
struct RowView: View {
#State var event:Event
var body: some View {
VStack {
Text(event.title)
.font(.headline)
Text(event.description)
.font(.subheadline)
}
}
}
struct ContentView: View {
#State var events:[Event] = [Event(view: Image("blue")),Event( view: Image("red")),Event( view: Image("green"))]
#State private var editMode = EditMode.inactive
var body: some View {
NavigationView {
List() {
ForEach(events.indices, id: \.self) { elementID in
NavigationLink(
destination: RowView(event: events[elementID])) {
RowView(event: events[elementID])
}
.background(events[elementID].view)
.clipped()
}
}
.listRowInsets(.init(top: 0, leading: 0, bottom: 0, trailing: 0))
.navigationTitle("Events")
.navigationBarItems(leading: EditButton())
.environment(\.editMode, $editMode)
}
}
}
This is what's produced by the code as you can see there is a border around the background image still.
I don't know what your images are, but seems that should not be important. Here is a demo on replicated code using colors.
Tested with Xcode 12.1 / iOS 14.1
Modified parts (important highlighted in comments)
struct Event {
var description:String = "description"
var title:String = "Title"
var view:Color
}
struct ContentView: View {
#State var events:[Event] = [Event(view: .blue),Event( view: .red),Event( view: .green)]
#State private var editMode = EditMode.inactive
var body: some View {
NavigationView {
List() {
ForEach(events.indices, id: \.self) { elementID in
events[elementID].view.overlay( // << this !!
NavigationLink(
destination: RowView(event: events[elementID])) {
RowView(event: events[elementID])
})
}
.listRowInsets(EdgeInsets()) // << this !!
}
.listStyle(PlainListStyle()) // << and this !!
.navigationTitle("Events")
.navigationBarItems(leading: EditButton())
.environment(\.editMode, $editMode)
}
}
}
This works:
struct RowView: View {
#State var event:Event
var body: some View {
VStack(alignment: .leading) {
Text(event.title)
.font(.headline)
Text(event.description)
.font(.subheadline)
}
.padding(10)
.foregroundColor(.yellow)
}
}
struct ContentView: View {
#State var events:[Event] = [Event(view: Image("blue")),Event( view: Image("red")),Event( view: Image("green"))]
#State private var editMode = EditMode.inactive
var body: some View {
NavigationView {
List() {
ForEach(events.indices, id: \.self) { elementID in
NavigationLink(
destination: RowView(event: events[elementID])) {
RowView(event: events[elementID])
}
.background(events[elementID].view
.resizable()
.aspectRatio(contentMode: .fill)
)
.clipped()
}
.listRowInsets(EdgeInsets())
}
.listStyle(PlainListStyle())
.navigationTitle("Events")
.navigationBarItems(leading: EditButton())
.environment(\.editMode, $editMode)
}
}
}
This is a derivative of Asperi's answer, so you can accept his answer, but this works with images, and no overlay. Tested on Xcode 12.1, IOS 14.1.
Here is an image where I grabbed arbitrary sized images for "red", "green", and "blue" from Goggle. I took the liberty of changing the row text to yellow so it would show up better.

PickerView disabled and doesn't work in SwiftUI

I don't understand why picker view doesn't work. I used this code:
import SwiftUI
struct NewChecklistItemView: View {
var colors = ["Red", "Green", "Blue", "Tartan"]
#State private var selectedColor = 0
var checklist: Checklist
#State var newItemName: String = ""
#Environment(\.presentationMode) var presentationMode
var body: some View {
VStack {
Text("Add new item")
Form {
TextField("Enter new item name here", text: $newItemName)
Picker(selection: $selectedColor, label: Text("Please choose a color")) {
ForEach(0 ..< colors.count) {
Text(self.colors[$0])
}
}
Text("You selected: \(colors[selectedColor])")
Button(action: {
//let newChecklistItem = Category(title: "Category", items: [ChecklistItem(name: self.newItemName)])
let newItem = ChecklistItem(name: self.newItemName)
self.checklist.items[0].items.append(newItem)
self.checklist.printChecklistContents()
self.presentationMode.wrappedValue.dismiss()
}) {
HStack {
Image(systemName: "plus.circle.fill")
Text("Add new item")
}
}
.disabled(newItemName.count == 0)
}
Text("Swipe down to cancel.")
}
}
}
struct NewChecklistItemView_Previews: PreviewProvider {
static var previews: some View {
NewChecklistItemView(checklist: Checklist())
}
}
PickerView is grey and disabled. So I cannot pick values. What could be the problem? I tried to move pickerView, but it doesn't help.
To make Picker work in Form you have to embed it into NavigationView, like
NavigationView {
Text("Add new item")
Form {
TextField("Enter new item name here", text: $newItemName)
Picker(selection: $selectedColor, label: Text("Please choose a color")) {
(of course, this might require some redesign/relayout)... or use different style picker style.

Cannot add something to an Array

i have made an app in SwiftUI where you can create different classes. The app saves this in an array. I have a textfield and a button in the same view as the scrollview that displays the array. This works perfectly fine and I can easily add new classes. Now I made a new view with a text field and a button. This view can be viewed by pressing a button in the nav bar. It uses the exact same function as the other view, but in the other view adding a item to the array works, in this view it doesn't work. I hope you understand my problem and can help me.
Thank You.
This is the file where I store the array:
import Foundation
import SwiftUI
import Combine
struct Class: Identifiable {
var name: String
var id = UUID()
}
class ClassStore: ObservableObject {
#Published var classes = [Class]()
}
This is the view with the button + textfield that works and the scrollview that displays the array:
import SwiftUI
struct ContentView: View {
#State var showNewClass = false
#ObservedObject var classStore = ClassStore()
#State var newClass: String = ""
#State var toDoColor: Color = Color.pink
func addNewClass() {
classStore.classes.append(
Class(name: newClass)
)
newClass = ""
}
var body: some View {
NavigationView {
VStack {
HStack {
TextField("New Todo", text: $newClass)
Image(systemName: "app.fill")
.foregroundColor(Color.pink)
.padding(.horizontal, 3)
Image(systemName: "books.vertical")
.padding(.horizontal, 3)
if newClass == "" {
Text("Add!")
.foregroundColor(Color.gray)
} else {
Button(action: {
addNewClass()
}) {
Text("Add!")
}
}
}.padding()
ScrollView {
ForEach(self.classStore.classes) { name in
Text(name.name)
}
}
.navigationBarTitle(Text("Schulnoten"))
.navigationBarItems(trailing:
Button(action: {
self.showNewClass.toggle()
}) {
Text("New Class")
}
.sheet(isPresented: $showNewClass) {
NewClass(isPresented: $showNewClass)
})
}
}
}
}
And this is the new view I created, the button and the textfield have the exact same code, but somehow this doesn't work:
import SwiftUI
struct NewClass: View {
#Binding var isPresented: Bool
#State var className: String = ""
#ObservedObject var classStore = ClassStore()
func addNewClass() {
classStore.classes.append(
Class(name: className)
)
}
var body: some View {
VStack {
HStack {
Text("New Class")
.font(.title)
.fontWeight(.semibold)
Spacer()
}
TextField("Name of the class", text: $className)
.padding()
.background(Color.gray)
.cornerRadius(5)
.padding(.vertical)
Button(action: {
addNewClass()
self.isPresented.toggle()
}) {
HStack {
Text("Safe")
.foregroundColor(Color.white)
.fontWeight(.bold)
.font(.system(size: 20))
}
.padding()
.frame(width: 380, height: 60)
.background(Color.blue)
.cornerRadius(5)
}
Spacer()
}.padding()
}
}
Sorry if my English is not that good. I'm not a native speaker.
I assume you should pass same class store from parent view into sheet, ie
struct NewClass: View {
#Binding var isPresented: Bool
#State var className: String = ""
#ObservedObject var classStore: ClassStore // << expect external
and in ContentView
.sheet(isPresented: $showNewClass) {
NewClass(isPresented: $showNewClass, classStore: self.classStore) // << here !!
})

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