I am building a small app using SwiftUI and Core Data. I have a main view, which launches the sheet. The sheet allows me to add a new movie to the SQLite database through Core Data. But I am having a hard time to refresh the parent view once the sheet is dismissed.
ContentView
struct ContentView: View {
#State private var isPresented: Bool = false
#StateObject private var vm = MovieListViewModel()
var body: some View {
NavigationView {
VStack {
List(vm.movies) { movie in
Text(movie.title)
}
}
.navigationTitle("Movies")
.toolbar(content: {
ToolbarItem(placement: .navigationBarTrailing) {
Button("Add Movie") {
isPresented = true
}
}
})
.sheet(isPresented: $isPresented, content: {
AddMovieView()
})
.onAppear {
try? vm.populateMovies()
}.padding()
}
}
}
AddMovieView
struct AddMovieView: View {
#Environment(\.dismiss) private var dismiss
#StateObject private var vm = AddMovieViewModel()
var body: some View {
Form {
TextField("Title", text: $vm.title)
Button("Save") {
do {
try vm.saveMovie()
dismiss()
} catch {
print(error.localizedDescription)
}
}
}
}
}
Do I need to call vm.populateMovies() on the onDismiss function of the sheet from the ContentView?
You can use a #FetchRequest as follows:
struct ContentView: View {
#FetchRequest(sortDescriptors: []) var movies: FetchedResults<Movie>
#State private var isPresented: Bool = false
#StateObject private var vm = MovieListViewModel()
var body: some View {
NavigationView {
VStack {
List(movies) { movie in
Text(movie.title)
}
}
.navigationTitle("Movies")
.toolbar(content: {
ToolbarItem(placement: .navigationBarTrailing) {
Button("Add Movie") {
isPresented = true
}
}
})
.sheet(isPresented: $isPresented, content: {
AddMovieView()
})
.padding()
}
}
}
You won't need a populateMovies() as the FetchRequest result is automatically populated.
I'm trying to figure how can change the value from different View. Here is the implementation of my main view:
import SwiftUI
import Combine
struct ContentView: View {
#State private var isPresented: Bool = false
#State private var textToProces = "" {
didSet{
print("text: oldValue=\(oldValue) newValue=\(textToProces)")
}
}
var body: some View {
ZStack{
VStack{
Button("Show Alert"){
self.isPresented = true
}.background(Color.blue)
}
ItemsAlertView(isShown: $isPresented, textToProcess: $textToProces)
}
}
}
On this view I'm trying to change the textToProces variable:
struct AnotherView: View {
#Binding var isShown: Bool
#Binding var textToProcess: String
var title: String = "Add Item"
let screenSize = UIScreen.main.bounds
var body: some View {
VStack {
Button(action: {
self.textToProcess = "New text"
self.isShown = false
}, label: {
Text("dissmis")
})
Text(self.textToProcess)
}
.background(Color.red)
.offset(y: isShown ? 0 : screenSize.height)
}
}
When I change the value on this line self.textToProcess = "New text" the textToProcess in the main view never gets the notification of the change. What I can I do to get the notification of the change in the main view any of you knows?
I'll really appreciate your help
You have to use the onChange modifier to track changes to textToProces.
import SwiftUI
import Combine
struct ContentView: View {
#State private var isPresented: Bool = false
#State private var textToProces = ""
var body: some View {
ZStack{
VStack{
Button("Show Alert"){
self.isPresented = true
}.background(Color.blue)
}
ItemsAlertView(isShown: $isPresented, textToProcess: $textToProces)
}
.onChange(of: textToProces) { value in
print("text: \(value)")
}
}
}
When using NavigationLink on the bottom of a view after ForEach it won't work if it is not visible.
I have a list of Buttons. If a button is pressed, it sets a Bool to true. This bool value now shows a NavigationLink which immediately activates because the passed binding is set to true.
However, the link won't work if the array is too long because it will be out of sight once one of the first buttons is pressed.
This is my Code:
import SwiftUI
struct TestLinkView: View {
#State private var linkIsActive = false
var body: some View {
NavigationView {
VStack {
Button(action: {
linkIsActive = true
}) {
Text("Press")
}
NavigationLink(destination: ListView(linkIsActive: $linkIsActive), isActive: $linkIsActive) {
Text("Navigation Link")
}
}
}
}
}
struct ListView: View {
var nameArray = ["Name1","Name2","Name3","Name4","Name5","Name6","Name7","Name8","Name9","Name10","Name11","Name12","Name13","Name14","Name15","Name16","Name17","Name18","Name19","Name20" ]
#State private var showLink: Bool = false
#State private var selectedName: String = ""
#Binding var linkIsActive: Bool
var body: some View {
Form {
ForEach(nameArray, id: \.self) { name in
Button(action: {
selectedName = name
showLink = true
}) {
Text(name)
}
}
if showLink {
NavigationLink(destination: NameView(selectedName: selectedName), isActive: $linkIsActive) {
EmptyView()
}
}
}
.navigationBarTitle("ListView")
}
}
struct NameView: View {
var selectedName: String
var body: some View {
Text(selectedName)
.navigationBarTitle("NameView")
}
}
What would work is to pass the NavigationLink with the if-condition inside the button label. However if I do that, the animation won't work anymore.
You don't need it in Form, which is like a List don't create views far outside of visible area. In your case the solution is to just move link into background of Form (because it does not depend on form internals).
The following tested as worked with Xcode 12 / iOS 14.
Form {
ForEach(nameArray, id: \.self) { name in
Button(action: {
selectedName = name
showLink = true
}) {
Text(name)
}
}
}
.background(Group{
if showLink {
NavigationLink(destination: NameView(selectedName: selectedName), isActive: $linkIsActive) {
EmptyView()
}
}
})
When I'm trying to dismiss/cancel an Add Object Modal, it is creating an empty object instead of just cancelling.
I've tried deleteObject, context.rollback(), and a bunch of other random things. Would love some help and able to answer any questions.
I realize that this isn't an issue by putting the Cancel button in a NavigationBarItem but would like to be able to understand how to make an separate "cancel (or dismiss)" button.
ContentView.swift
import SwiftUI
import CoreData
struct ContentView: View {
#Environment(\.managedObjectContext) var moc
#FetchRequest(entity: Game.entity(), sortDescriptors: [NSSortDescriptor(keyPath: \Game.gameName, ascending: true)]) var games: FetchedResults<Game>
#State private var showingAddGame = false
var body: some View {
GeometryReader { geometry in
NavigationView {
List {
ForEach(self.games, id: \.self) { games in
NavigationLink(destination: GameGoalsDetail(game: games)) {
VStack(alignment: .leading) {
Text(games.gameName ?? "Unknown Game")
Text(games.gameDescription ?? "Unknown Game Description")
}
}
}
.onDelete(perform: self.removeGames)
}
.navigationBarItems(leading:
HStack {
Button(action: {
self.showingAddGame.toggle()
}) {
Text("Add Game")
.padding(.top, 50)
.foregroundColor(Color.yellow)
}.sheet(isPresented: self.$showingAddGame) {
AddGameView().environment(\.managedObjectContext, self.moc)
}
Image("Game Goals App Logo")
.resizable()
.frame(width: 100, height: 100)
.padding(.leading, (geometry.size.width / 2.0) + -160)
.padding(.bottom, -50)
}, trailing:
EditButton()
.padding(.top, 50)
.foregroundColor(Color.yellow)
)
}
}
}
func removeGames(at offsets: IndexSet) {
for index in offsets {
let game = games[index]
moc.delete(game)
}
try? moc.save()
}
}
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
let context = (UIApplication.shared.delegate as! AppDelegate).persistentContainer.viewContext
let newGame = Game(context: context)
newGame.gameName = "Apex Legends"
newGame.gameDescription = "Maybe this will work"
return ContentView().environment(\.managedObjectContext, context)
}
}
AddGameView.swift
import SwiftUI
import CoreData
struct AddGameView: View {
#Environment(\.managedObjectContext) var moc
#FetchRequest(entity: Game.entity(), sortDescriptors: []) var games: FetchedResults<Game>
#Environment(\.presentationMode) var presentationMode
#State private var gameName = ""
#State private var gameDescription = ""
#State private var showingAlert = false
var body: some View {
Form {
Section {
TextField("Game Name", text: $gameName)
TextField("Game Description", text: $gameDescription)
}
HStack {
Button("Add Game") {
let newGame = Game(context: self.moc)
newGame.gameName = self.gameName
newGame.gameDescription = self.gameDescription
do {
try self.moc.save()
self.presentationMode.wrappedValue.dismiss()
} catch {
print("Whoops! \(error.localizedDescription)")
}
}
Button(action: {
self.presentationMode.wrappedValue.dismiss()
}) {
Text("Cancel")
}
.padding(10)
.foregroundColor(Color.white)
.background(Color.red)
}
}
}
}
struct AddGameView_Previews: PreviewProvider {
static var previews: some View {
AddGameView()
}
}
I've searched all over so if there is something out there that I've missed as far as a stackoverflow post, please link it as I'd like to not only fix this but understand why.
Your Cancel button is not creating an empty object. The problem is that the whole row in your form that has Add and Cancel buttons is interactive and triggers actions of your both buttons.
I have found an answer here: https://stackoverflow.com/a/59402642/12315994
To keep your current layout you need to simply add one line to each of your buttons:
.buttonStyle(BorderlessButtonStyle())
After this, only taping on each button will trigger actions. Form's row with the buttons will not be clickable.
There are 2 other solutions. Both are to move your buttons out of Form.
Solution 1
is to move buttons to NavigationBarItems like this:
import SwiftUI
import CoreData
struct AddGameView: View {
#Environment(\.managedObjectContext) var moc
#FetchRequest(entity: Game.entity(), sortDescriptors: []) var games: FetchedResults<Game>
#Environment(\.presentationMode) var presentationMode
#State private var gameName = ""
#State private var gameDescription = ""
#State private var showingAlert = false
var body: some View {
NavigationView {
VStack {
Form {
Section {
TextField("Game Name", text: $gameName)
TextField("Game Description", text: $gameDescription)
}
}
}
.navigationBarItems(
leading:
Button(action: {
self.presentationMode.wrappedValue.dismiss()
}) {
Text("Cancel")
}
.padding(10)
.foregroundColor(Color.white)
.background(Color.red)
,
trailing:
Button(action: {
let newGame = Game(context: self.moc)
newGame.gameName = self.gameName
newGame.gameDescription = self.gameDescription
do {
try self.moc.save()
self.presentationMode.wrappedValue.dismiss()
} catch {
print("Whoops! \(error.localizedDescription)")
}
}) {
Text("Add Game")
}
)
}
}
}
Solution 2
Is to move buttons out of Form and move them to the bottom of the screen. Like this:
import SwiftUI
import CoreData
struct AddGameView: View {
#Environment(\.managedObjectContext) var moc
#FetchRequest(entity: Game.entity(), sortDescriptors: []) var games: FetchedResults<Game>
#Environment(\.presentationMode) var presentationMode
#State private var gameName = ""
#State private var gameDescription = ""
#State private var showingAlert = false
var body: some View {
VStack {
Form {
Section {
TextField("Game Name", text: $gameName)
TextField("Game Description", text: $gameDescription)
}
}
HStack {
Button(action: {
let newGame = Game(context: self.moc)
newGame.gameName = self.gameName
newGame.gameDescription = self.gameDescription
do {
try self.moc.save()
self.presentationMode.wrappedValue.dismiss()
} catch {
print("Whoops! \(error.localizedDescription)")
}
}) {
Text("Add Game")
}
Button(action: {
self.presentationMode.wrappedValue.dismiss()
}) {
Text("Cancel")
}
.padding(10)
.foregroundColor(Color.white)
.background(Color.red)
}
}
}
}
Both options are better than your current layout from the UX point of view, because buttons are now in more standard locations. Especially version 1 is a more standard way of presenting buttons like this in iOS.
I was playing around with SwiftUI and want to be able to come back to the previous view when tapping a button, the same we use popViewController inside a UINavigationController.
Is there a provided way to do it so far ?
I've also tried to use NavigationDestinationLink to do so without success.
struct AView: View {
var body: some View {
NavigationView {
NavigationButton(destination: BView()) {
Text("Go to B")
}
}
}
}
struct BView: View {
var body: some View {
Button(action: {
// Trying to go back to the previous view
// previously: navigationController.popViewController(animated: true)
}) {
Text("Come back to A")
}
}
}
Modify your BView struct as follows. The button will perform just as popViewController did in UIKit.
struct BView: View {
#Environment(\.presentationMode) var mode: Binding<PresentationMode>
var body: some View {
Button(action: { self.mode.wrappedValue.dismiss() })
{ Text("Come back to A") }
}
}
Use #Environment(\.presentationMode) var presentationMode to go back previous view. Check below code for more understanding.
import SwiftUI
struct ContentView: View {
var body: some View {
NavigationView {
ZStack {
Color.gray.opacity(0.2)
NavigationLink(destination: NextView(), label: {Text("Go to Next View").font(.largeTitle)})
}.navigationBarTitle(Text("This is Navigation"), displayMode: .large)
.edgesIgnoringSafeArea(.bottom)
}
}
}
struct NextView: View {
#Environment(\.presentationMode) var presentationMode
var body: some View {
ZStack {
Color.gray.opacity(0.2)
}.navigationBarBackButtonHidden(true)
.navigationBarItems(leading: Button(action: {
self.presentationMode.wrappedValue.dismiss()
}, label: { Image(systemName: "arrow.left") }))
.navigationBarTitle("", displayMode: .inline)
}
}
struct NameRow: View {
var name: String
var body: some View {
HStack {
Image(systemName: "circle.fill").foregroundColor(Color.green)
Text(name)
}
}
}
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView()
}
}
With State Variables. Try that.
struct ContentViewRoot: View {
#State var pushed: Bool = false
var body: some View {
NavigationView{
VStack{
NavigationLink(destination:ContentViewFirst(pushed: self.$pushed), isActive: self.$pushed) { EmptyView() }
.navigationBarTitle("Root")
Button("push"){
self.pushed = true
}
}
}
.navigationViewStyle(StackNavigationViewStyle())
}
}
struct ContentViewFirst: View {
#Binding var pushed: Bool
#State var secondPushed: Bool = false
var body: some View {
VStack{
NavigationLink(destination: ContentViewSecond(pushed: self.$pushed, secondPushed: self.$secondPushed), isActive: self.$secondPushed) { EmptyView() }
.navigationBarTitle("1st")
Button("push"){
self.secondPushed = true;
}
}
}
}
struct ContentViewSecond: View {
#Binding var pushed: Bool
#Binding var secondPushed: Bool
var body: some View {
VStack{
Spacer()
Button("PopToRoot"){
self.pushed = false
} .navigationBarTitle("2st")
Spacer()
Button("Pop"){
self.secondPushed = false
} .navigationBarTitle("1st")
Spacer()
}
}
}
This seems to work for me on watchOS (haven't tried on iOS):
#Environment(\.presentationMode) var presentationMode
And then when you need to pop
self.presentationMode.wrappedValue.dismiss()
There is now a way to programmatically pop in a NavigationView, if you would like. This is in beta 5.
Notice that you don't need the back button. You could programmatically trigger the showSelf property in the DetailView any way you like. And you don't have to display the "Push" text in the master. That could be an EmptyView(), thereby creating an invisible segue.
(The new NavigationLink functionality takes over the deprecated NavigationDestinationLink)
import SwiftUI
struct ContentView: View {
var body: some View {
NavigationView {
MasterView()
}
}
}
struct MasterView: View {
#State var showDetail = false
var body: some View {
VStack {
NavigationLink(destination: DetailView(showSelf: $showDetail), isActive: $showDetail) {
Text("Push")
}
}
}
}
struct DetailView: View {
#Binding var showSelf: Bool
var body: some View {
Button(action: {
self.showSelf = false
}) {
Text("Pop")
}
}
}
#if DEBUG
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView()
}
}
#endif
It seems that a ton of basic navigation functionality is super buggy, which is disappointing and may be worth walking away from for now to save hours of frustration. For me, PresentationButton is the only one that works. TabbedView tabs don't work properly, and NavigationButton doesn't work for me at all. Sounds like YMMV if NavigationButton works for you.
I'm hoping that they fix it at the same time they fix autocomplete, which would give us much better insight as to what is available to us. In the meantime, I'm reluctantly coding around it and keeping notes for when fixes come out. It sucks to have to figure out if we're doing something wrong or if it just doesn't work, but that's beta for you!
Update: the NavigationDestinationLink API in this solution has been deprecated as of iOS 13 Beta 5. It is now recommended to use NavigationLink with an isActive binding.
I figured out a solution for programmatic pushing/popping of views in a NavigationView using NavigationDestinationLink.
Here's a simple example:
import Combine
import SwiftUI
struct DetailView: View {
var onDismiss: () -> Void
var body: some View {
Button(
"Here are details. Tap to go back.",
action: self.onDismiss
)
}
}
struct MainView: View {
var link: NavigationDestinationLink<DetailView>
var publisher: AnyPublisher<Void, Never>
init() {
let publisher = PassthroughSubject<Void, Never>()
self.link = NavigationDestinationLink(
DetailView(onDismiss: { publisher.send() }),
isDetail: false
)
self.publisher = publisher.eraseToAnyPublisher()
}
var body: some View {
VStack {
Button("I am root. Tap for more details.", action: {
self.link.presented?.value = true
})
}
.onReceive(publisher, perform: { _ in
self.link.presented?.value = false
})
}
}
struct RootView: View {
var body: some View {
NavigationView {
MainView()
}
}
}
I wrote about this in a blog post here.
You can also do it with .sheet
.navigationBarItems(trailing: Button(action: {
self.presentingEditView.toggle()
}) {
Image(systemName: "square.and.pencil")
}.sheet(isPresented: $presentingEditView) {
EditItemView()
})
In my case I use it from a right navigation bar item, then you have to create the view (EditItemView() in my case) that you are going to display in that modal view.
https://developer.apple.com/documentation/swiftui/view/sheet(ispresented:ondismiss:content:)
EDIT: This answer over here is better than mine, but both work: SwiftUI dismiss modal
What you really want (or should want) is a modal presentation, which several people have mentioned here. If you go that path, you definitely will need to be able to programmatically dismiss the modal, and Erica Sadun has a great example of how to do that here: https://ericasadun.com/2019/06/16/swiftui-modal-presentation/
Given the difference between declarative coding and imperative coding, the solution there may be non-obvious (toggling a bool to false to dismiss the modal, for example), but it makes sense if your model state is the source of truth, rather than the state of the UI itself.
Here's my quick take on Erica's example, using a binding passed into the TestModal so that it can dismiss itself without having to be a member of the ContentView itself (as Erica's is, for simplicity).
struct TestModal: View {
#State var isPresented: Binding<Bool>
var body: some View {
Button(action: { self.isPresented.value = false }, label: { Text("Done") })
}
}
struct ContentView : View {
#State var modalPresented = false
var body: some View {
NavigationView {
Text("Hello World")
.navigationBarTitle(Text("View"))
.navigationBarItems(trailing:
Button(action: { self.modalPresented = true }) { Text("Show Modal") })
}
.presentation(self.modalPresented ? Modal(TestModal(isPresented: $modalPresented)) {
self.modalPresented.toggle()
} : nil)
}
}
Below works for me in XCode11 GM
self.myPresentationMode.wrappedValue.dismiss()
instead of NavigationButton use Navigation DestinationLink
but You should import Combine
struct AView: View {
var link: NavigationDestinationLink<BView>
var publisher: AnyPublisher<Void, Never>
init() {
let publisher = PassthroughSubject<Void, Never>()
self.link = NavigationDestinationLink(
BView(onDismiss: { publisher.send() }),
isDetail: false
)
self.publisher = publisher.eraseToAnyPublisher()
}
var body: some View {
NavigationView {
Button(action:{
self.link.presented?.value = true
}) {
Text("Go to B")
}.onReceive(publisher, perform: { _ in
self.link.presented?.value = false
})
}
}
}
struct BView: View {
var onDismiss: () -> Void
var body: some View {
Button(action: self.onDismiss) {
Text("Come back to A")
}
}
}
In the destination pass the view you want to redirect, and inside block pass data you to pass in another view.
NavigationLink(destination: "Pass the particuter View") {
Text("Push")
}