I have a view, where i can add a new entry to CoreData. The name for that entry cannot be null, which can be seen in the ViewModel. If someone tries to add a new entry without a name, they are presented with an error. Now, every time the error pops up, it dismisses itself.
The View:
struct AddProductPopover: View {
#Environment(\.presentationMode) var presentationMode
#StateObject var prodPopViewModel = AddProductPopoverViewModel()
var body: some View {
NavigationView {
List {
HStack {
Label("", systemImage: K.ProductIcons.name)
.foregroundColor(.black)
Spacer().frame(maxWidth: .infinity)
TextField("Add Name", text: $prodPopViewModel.newProductName)
.keyboardType(.default)
}
}
.toolbar {
ToolbarItem(placement: .navigationBarTrailing) {
Button("Save") {
prodPopViewModel.saveProduct()
// if saving fails due to an empty name, the dismissal is still called before the error is displayed
presentationMode.wrappedValue.dismiss()
}
.alert(isPresented: $prodPopViewModel.showAlert) {
Alert(
title: Text("Product Name cannot be empty!"),
message: Text("Please specify a name for your new Product.")
)
}
}
}
}
}
The ViewModel:
class AddProductPopoverViewModel: ObservableObject {
var managedObjectContext = PersistenceController.shared.container.viewContext
#Published var newProductName: String = ""
#Published var newProductVendor: String = ""
#Published var newProductCategory: String = ""
#Published var newProductStoredQuantity: Int = 0
#Published var showAlert = false
func saveProduct() {
// if name is not nil saves the new product to CoreData
if !newProductName.isEmpty {
let newProduct = ProductEntity(context: managedObjectContext)
newProduct.productName = newProductName
newProduct.id = UUID()
newProduct.productVendor = newProductVendor
newProduct.productCategory = newProductCategory
newProduct.productStoredQuantity = Int32(newProductStoredQuantity)
PersistenceController.shared.save()
} else {
showAlert = true
}
}
I have figured out, that issue lies in the View in the Button Save action. Whenever the check in the ViewModel fails, it sets the boolean required for the alert to true. However, after setting that boolean to true, it returns to the view first and completes the next step in the Button Action, which is dismissing the current view before it then finally triggers the Alert. This execution order results in the Alert to be dismissed. However, the alert should not be dismissed. Dismissing should only happen if saving to CoreData has been successfull.
Button("Save") {
prodPopViewModel.saveProduct()
presentationMode.wrappedValue.dismiss()
}
What changes would I need to make to skip the dismissing line in case the boolean is set to true? I thought of including the dismissal in the ViewModel. However, that would violate the MVVM concept I'm trying to follow.
Replace save button with:
Button("Save") {
prodPopViewModel.saveProduct() // save the product
if (!prodPopViewModel.showAlert) { // don't dismiss if need to show alert
presentationMode.wrappedValue.dismiss()
}
}
.alert("Product Name cannot be empty!", // alert title
// decide to show alert i.e. save failed
isPresented: $prodPopViewModel.showAlert) {
Button("Ok"){
// hide alert on button press
prodPopViewModel.showAlert = false
}
} message: {
Text("Please specify a name for your new Product.")
}
Related
I am passing a Person binding from the first view to the second view to the third view, when I update the binding value in the third view it pops back to the second view, I understand that SwiftUI updates the views that depend on the state value, but is poping the current view is the expected behavior or I am doing something wrong?
struct Person: Identifiable {
let id = UUID()
var name: String
var numbers = [1, 2]
}
struct FirstView: View {
#State private var people = [Person(name: "Current Name")]
var body: some View {
NavigationView {
List($people) { $person in
NavigationLink(destination: SecondView(person: $person)) {
Text(person.name)
}
}
}
}
}
struct SecondView: View {
#Binding var person: Person
var body: some View {
Form {
NavigationLink(destination: ThirdView(person: $person)) {
Text("Update Info")
}
}
}
}
struct ThirdView: View {
#Binding var person: Person
var body: some View {
Form {
Button(action: {
person.numbers.append(3)
}) {
Text("Append a new number")
}
}
}
}
When navigating twice you need to either use isDetailLink(false) or StackNavigationViewStyle, e.g.
struct FirstView: View {
#State private var people = [Person(name: "Current Name")]
var body: some View {
NavigationView {
List($people) { $person in
NavigationLink(destination: SecondView(person: $person)) {
Text(person.name)
}
.isDetailLink(false) // option 1
}
}
.navigationViewStyle(.stack) // option 2
}
}
SwiftUI works by updating the rendered views to match what you have in your state.
In this case, you first have a list that contains an element called Current Name. Using a NavigationLink you select this item.
You update the name and now that previous element no longer exists, it's been replaced by a new element called New Name.
Since Current Name no longer exists, it also cannot be selected any longer, and the view pops back to the list.
To be able to edit the name without popping back, you'll need to make sure that the item on the list is the same, even if the name has changed. You can do this by using an Identifiable struct instead of a String.
struct Person: Identifiable {
let id = UUID().uuidString
var name = "Current Name"
}
struct ParentView: View {
#State private var people = [Person()]
var body: some View {
NavigationView {
List($people) { $person in
NavigationLink(destination: ChildView(person: $person)) {
Text(person.name)
}
}
}
}
}
struct ChildView: View {
#Binding var person: Person
var body: some View {
Button(action: {
person.name = "New Name"
}) {
Text("Update Name")
}
}
}
I am using coredata to save information. This information populates a picker, but at the moment there is no information so the picker is empty. The array is set using FetchedRequest.
#FetchRequest(sortDescriptors: [])
var sources: FetchedResults<Source>
#State private var selectedSource = 0
This is how the picker is setup.
Picker(selection: $selectedSource, label: Text("Source")) {
ForEach(0 ..< sources.count) {
Text(sources[$0].name!)
}
}
There is also a button that displays another sheet and allows the user to add a source.
Button(action: { addSource.toggle() }, label: {
Text("Add Source")
})
.sheet(isPresented: $addSource, content: {
AddSource(showSheet: $addSource)
})
If the user presses Add Source, the sheet is displayed with a textfield and a button to add the source. There is also a button to dismiss the sheet.
struct AddSource: View {
#Environment(\.managedObjectContext) var viewContext
#Binding var showSheet: Bool
#State var name = ""
var body: some View {
NavigationView {
Form {
Section(header: Text("Source")) {
TextField("Source Name", text: $name)
Button("Add Source") {
let source = Source(context: viewContext)
source.name = name
do {
try viewContext.save()
name = ""
} catch {
let error = error as NSError
fatalError("Unable to save context: \(error)")
}
}
}
}
.navigationBarTitle("Add Source")
.navigationBarItems(trailing: Button(action:{
self.showSheet = false
}) {
Text("Done").bold()
.accessibilityLabel("Add your source.")
})
}
}
}
Once the sheet is dismissed, it goes back to the first view. The picker in the first view is not updated with the newly added source. You have to close it and reopen. How can I update the picker once the source is added by the user? Thanks!
The issue is with the ForEach signature you're using. It works only for constant data. If you want to use with changing data, you have to use something like:
ForEach(sources, id: \Source.name.hashValue) {
Text(verbatim: $0.name!)
}
Note that hashValue will not be unique for two entity objects with the same name. This is just an example
From a settings page, I want to :
Navigate to a child view
Let the user input update some value in a textfield
Save this value in the user defaults
Navigate back to the settings
If the user opens the child view again, pre-fill the textfield with the previously saved value
Given the following (simple) code :
// User defaults wrapper
class SettingsProvider: ObservableObject {
static let shared = SettingsProvider()
var savedValue: String {
get { UserDefaults.standard.string(forKey: "userdefaultskey") ?? "Default value" }
set {
UserDefaults.standard.setValue(newValue, forKey: "userdefaultskey")
objectWillChange.send()
}
}
}
struct SettingsView: View {
var body: some View {
NavigationView {
NavigationLink("Open child", destination: ChildView())
}
}
}
struct ChildView: View {
#ObservedObject var settingsProvider = SettingsProvider.shared
#State var text: String = SettingsProvider.shared.savedValue
var body: some View {
Text("Value is \(settingsProvider.savedValue)")
TextField("Enter value", text: $text).background(Color.gray)
Button("Save value") {
settingsProvider.savedValue = text
}
}
}
I'm having the following behaviour : video
Can somebody explain to me why the TextField contains Default value the second time I open it ?
Is it a bug in SwiftUI that I should report, or am I missing something ?
If I kill & re-open the app, the textfield will contain (as expected) Other value.
You can just add an onAppear { text = SettingsProvider.shared.savedValue } under the Button like this:
var body: some View {
Text("Value is \(settingsProvider.savedValue)")
TextField("Enter value", text: $text).background(Color.gray)
Button("Save value") {
settingsProvider.savedValue = text
}
.onAppear {
text = SettingsProvider.shared.savedValue // <= add this
}
}
The below swiftUI code was working fine with iOS13, but on testing with iOS14, I'm getting fatal errors caused by the force-unwrapped optional when trying to display the modal sheet. As far as I can tell, the sheet should never try to present with a nil value for selectedModel, as showingDetails is only ever made true after assigning selectedModel?
struct SpeakerBrandMenu: View {
var filteredSpeakers: [Speaker] {
// An array of Speaker objects
}
#State var selectedModel: Speaker?
#State private var showingDetails = false
var body: some View {
List{
ForEach(filteredSpeakers) { speaker in
HStack {
Button(action: {
self.selectedModel = speaker
self.showingDetails = true
}) {
SpeakerModelRow(speaker: speaker).contentShape(Rectangle())
}
.buttonStyle(PlainButtonStyle())
Spacer()
Button(
//unrelated
).padding(5)
}
}
} .sheet(isPresented: self.$showingDetails) { SpeakerDetailView(speaker: self.selectedModel!, showSheet: self.$showingDetails).environmentObject(self.favoriteSpeakers).environmentObject(self.settings)}
.navigationBarTitle(Text(brand), displayMode: .inline)
}
}
Interestingly, if I unwrap it as speaker: self.selectedModel ?? filteredSpeakers[0]it behaves exactly as expected: The first time pressing any of the menu items, the first item is passed to the sheet, but on dismissing the sheet and selecting another item it then shows the correct item every time. So it's as though the button to assign selectedModel is trying to display the sheet before it has had time assign it.
It looks like in iOS 14 the sheet(isPresented:content:) is now created beforehand, so any changes made to selectedModel are ignored.
Try using sheet(item:content:) instead:
var body: some View {
List {
...
}
.sheet(item: self.$selectedModel) {
SpeakerDetailView(speaker: $0)
}
}
and dismiss the sheet using #Environment(\.presentationMode):
struct SpeakerDetailView: View {
#Environment(\.presentationMode) private var presentationMode
var speaker: Speaker
var body: some View {
Text("Speaker view")
.onTapGesture {
presentationMode.wrappedValue.dismiss()
}
}
}
I have a sheet view that is presented when a user clicks a button as shown in the parent view below:
struct ViewWithSheet: View {
#State var showingSheetView: Bool = false
#EnvironmetObject var store: DataStore()
var body: some View {
NavigationView() {
ZStack {
Button(action: { self.showingSheetView = true }) {
Text("Show sheet view")
}
}
.navigationBarHidden(true)
.navigationBarTitle("")
.sheet(isPresented: $showingSheetView) {
SheetView(showingSheetView: self.$showingSheetView).environmentObject(self.dataStore)
}
}
}
}
In the sheet view, when a user clicks another button, an action is performed by the store that has a completion handler. The completion handler returns an object value, and if that value exists, should dismiss the SheetView.
struct SheetView: View {
#Binding var showingSheetView: Bool
#EnvironmentObject var store: DataStore()
//#Environment(\.presentationMode) private var presentationMode
func create() {
store.createObject() { object, error in
if let _ = object {
self.showingSheetView = false
// self.presentationMode.wrappedValue.dismiss()
}
}
}
var body: some View {
VStack {
VStack {
HStack {
Button(action: { self.showingSheetView = false }) {
Text("Cancel")
}
Spacer()
Spacer()
Button(action: { self.create() }) {
Text("Add")
}
}
.padding()
}
}
}
}
However, in the create() function, once the store returns values and showingSheetView is set to false, the sheet view doesn't dismiss as expected. I've tried using presentationMode to dismiss the sheet as well, but this also doesn't appear to work.
I found my issue, the sheet wasn't dismissing due to a conditional in my overall App wrapping View, I had an if statement that would show a loading view on app startup, however, in my DataStore I was setting it's fetching variable on every function call it performs. When that value changed, the view stack behind my sheet view would re-render the LoadingView and then my TabView once the fetching variable changed again. This was making the sheet view un-dismissable. Here's an example of what my AppView looked like:
struct AppView: View {
#State private var fetchMessage: String = ""
#EnvironmentObject var store: DataStore()
func initializeApp() {
self.fetchMessage = "Getting App Data"
store.getData() { object, error in
if let error = error {
self.fetchMessage = error.localizedDescription
}
self.fetchMessage = ""
}
}
var body: some View {
Group {
ZStack {
//this is where my issue was occurring
if(!store.fetching) {
TabView {
Tab1().tabItem {
Image(systemName: "tab-1")
Text("Tab1")
}
Tab2().tabItem {
Image(systemName: "tab-2")
Text("Tab2")
}
//Tab 3 contained my ViewWithSheet() and SheetView()
Tab3().tabItem {
Image(systemName: "tab-3")
Text("Tab3")
}
}
} else {
LoadingView(loadingMessage: $fetchMessage)
}
}
}.onAppear(perform: initializeApp)
}
}
To solve my issue, I added another variable to my DataStore called initializing, which I use to render the loading screen or the actual application views on first .onAppear event in my app. Below is an example of what my updated AppView looks like:
struct AppView: View {
#State private var fetchMessage: String = ""
#EnvironmentObject var store: DataStore()
func initializeApp() {
self.fetchMessage = "Getting App Data"
store.getData() { object, error in
if let error = error {
self.fetchMessage = error.localizedDescription
}
self.fetchMessage = ""
//set the value to false once I'm done getting my app's initial data.
self.store.initializing = false
}
}
var body: some View {
Group {
ZStack {
//now using initializing instead
if(!store.initializing) {
TabView {
Tab1().tabItem {
Image(systemName: "tab-1")
Text("Tab1")
}
Tab2().tabItem {
Image(systemName: "tab-2")
Text("Tab2")
}
//Tab 3 contained my ViewWithSheet() and SheetView()
Tab3().tabItem {
Image(systemName: "tab-3")
Text("Tab3")
}
}
} else {
LoadingView(loadingMessage: $fetchMessage)
}
}
}.onAppear(perform: initializeApp)
}
}
Try to do this on main queue explicitly
func create() {
store.createObject() { object, error in
if let _ = object {
DispatchQueue.main.async {
self.showingSheetView = false
}
}
// think also about feedback on else case as well !!
}
}
Want to see something hacky that worked for me? Disclaimer: Might not work for you and I don't necessarily recommend it. But maybe it'll help someone in a pinch.
If you add a NavigationLink AND keep your fullScreenCover, then the fullscreen cover will be able to dismiss itself like you expect.
Why does this happen when you add the NavigationLink to your View? I don't know. My guess is it creates an extra reference somewhere.
Add this to your body, and keep your sheet as it is:
NavigationLink(destination: YOURVIEW().environmentObjects(), isActive: $showingSheetView) {}