can someone please help me with this issue? I'm trying to detect the issue for like 2 hours now.
I want to switch view from LoginView() to RegistrationView() when button("Test") in LoginView() is pressed.
I did try this solution but it does nothing.
Any help is welcomed...
i have no idea how to change to registrationView()
struct mainView: View {
#State var show = false
var body: some View {
return Group {
if show {
RegistrationView()
}
}
}
}
struct LoginView : View {
#Binding var show: Bool
#StateObject private var loginVM = LoginViewModel()
var body: some View {
ZStack {BGimg()
if !loginVM.isAuthenticated {
VStack() {
.ignoresSafeArea(.all)
UsernameTextField(username: $loginVM.username)
PasswordSecureField(password: $loginVM.password)
ForgotPassword()
Button(action: loginVM.login) {
LoginButtonContent()
})
Button("Test") {
show.toggle()
}
}
.navigationBarHidden(false)
}
else if loginVM.isAuthenticated {
Home()
.navigationBarItems(trailing:
Button(action: loginVM.signout) {
Text("Sign out")
}
)
}
}
}
struct LoginView_Previews: PreviewProvider {
static var previews: some View {
LoginView()
.previewDevice("iPhone 12 Pro")
}
}
Related
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 am going to create a SwiftUI application where I want to be able to swap between 3 modes. I am trying EnvironmentObject without success. I am able to change the view displayed locally, but from another View (in the end will be a class) I get a
fatal error: No ObservableObject of type DisplayView found. A View.environmentObject(_:) for DisplayView may be missing as an ancestor of this view.
Here is my code. The first line of the ContentView if/else fails.
enum ViewMode {
case Connect, Loading, ModeSelection
}
class DisplayView: ObservableObject {
#Published var displayMode: ViewMode = .Connect
}
struct ContentView: View {
#EnvironmentObject var viewMode: DisplayView
var body: some View {
VStack {
if viewMode.displayMode == .Connect {
ConnectView()
} else if viewMode.displayMode == .Loading {
LoadingView()
} else if viewMode.displayMode == .ModeSelection {
ModeSelectView()
} else {
Text("Error.")
}
TestView() //Want this to update the var & change UI.
}
.environmentObject(viewMode)
}
}
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView()
.environmentObject(DisplayView())
}
}
//FAILS
struct TestView: View {
#EnvironmentObject var showView: DisplayView
var body: some View {
HStack {
Button("-> load") {
self.showView.displayMode = .Loading
}
}
}
}
struct ConnectView: View {
var body: some View {
Text("Connect...")
}
}
struct LoadingView: View {
var body: some View {
Text("Loading...")
}
}
struct ModeSelectView: View {
var body: some View {
Text("Select Mode")
}
}
I would like to be able to update DisplayView from anywhere and have the ContentView UI adapt accordingly. I can update from within ContentView but I want to be able update from anywhere and have my view change.
I needed to inject BEFORE - so this fixed things up:
#main
struct fooApp: App {
var body: some Scene {
WindowGroup {
ContentView()
.environmentObject(DisplayView()) //super key!
}
}
}
I also tried a Singleton class to store some properties - and thus they are available from anywhere and can be updated anywhere - without having to declare EnvironmentObject. It's just another way that can work in different circumstances.
class PropContainerModel {
public var foo = "Hello"
static let shared = PropContainerModel()
private override init(){}
}
And then somewhere else
let thisFoo = PropContainerModel.shared.foo
//
PropContainerModel.shared.foo = "There"
Update here (Singleton but changes reflect in the SwiftUI UI).
class PropContainerModel: ObservableObject
{
#Published var foo: String = "Foo"
static let shared = PropContainerModel()
private init(){}
}
struct ContentView: View
{
#ObservedObject var propertyModel = PropContainerModel.shared
var body: some View {
VStack {
Text("foo = \(propertyModel.foo)")
.padding()
Button {
tapped(value: "Car")
} label: {
Image(systemName:"car")
.font(.system(size: 24))
.foregroundColor(.black)
}
Spacer()
.frame(height:20)
Button {
tapped(value: "Star")
} label: {
Image(systemName:"star")
.font(.system(size: 24))
.foregroundColor(.black)
}
}
}
func tapped(value: String)
{
PropContainerModel.shared.foo = value
}
}
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView()
}
}
Very strange behavior.
Click the back button on the subpage (Subview) to return to the main page (ContentView). However, the subpage (Subview) automatically opens again. Why?
import SwiftUI
struct ContentView: View {
#State var things: [String] = []
#State var count: Int = 0
var body: some View {
NavigationView{
List {
ForEach(things.indices, id: \.self) { index in
Text(things[index])
}
}
.onAppear {
update()
}
.navigationTitle("a")
.toolbar{
NavigationLink(destination: Subview(count: $count), label: {
Text("sub")
})
}
}
}
func update() {
things = []
for i in 0...count {
things.append(String(i))
}
}
}
struct Subview: View {
var count : Binding<Int>
var body: some View {
Text("sub")
.onAppear {
count.wrappedValue += 1
}
}
}
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView()
}
}
NavigationLink should always be inside a NavigationView. If you put it in the toolbar or some other place, you might run into weird issues.
Instead, use the init(destination:isActive:label:) initializer. Then set the presentingNextPage property to true when you want to present the next page.
struct ContentView: View {
#State var things: [String] = []
#State var count: Int = 0
#State var presentingNextPage = false
var body: some View {
NavigationView {
List {
ForEach(things.indices, id: \.self) { index in
Text(things[index])
}
/// placeholder navigation link
NavigationLink(destination: Subview(count: $count), isActive: $presentingNextPage) {
EmptyView()
}
}
.onAppear {
self.update()
}
.navigationTitle("a")
.toolbar{
ToolbarItem(placement: .navigationBarTrailing) {
Button("sub") {
presentingNextPage = true /// set to true
}
}
}
}
}
func update() {
things = []
for i in 0...count {
things.append(String(i))
}
}
}
Result:
Put "onAppear{...}" on the NavigationView not the List, like this:
struct ContentView: View {
#State var things: [String] = []
#State var count: Int = 0
var body: some View {
NavigationView{
List {
ForEach(things.indices, id: \.self) { index in
Text(things[index])
}
}
.navigationTitle("a")
.toolbar{
NavigationLink(destination: Subview(count: $count), label: {
Text("sub")
})
}
}
.onAppear { // <---
update()
}
}
I have 2 Views in my Swift Project and when I click on the Button on the secondView, I want to update the List in the First View. I don't know how to do it! If I use a static variable in my MainView and then edit this variable from the secondView, it works, but it won't update. And if I don't use static and instead use #State, it would update, but I can't access it from my secondView.
Here is the Code below:
import SwiftUI
struct ContentView: View {
var body: some View {
TabView {
MainView()
.tabItem() {
VStack {
Image(systemName: "circle.fill")
Text("MainView")
}
}.tag(0)
UpdateOtherViewFromHere()
.tabItem() {
VStack {
Image(systemName: "circle.fill")
Text("SecondView")
}
}.tag(1)
}
}
}
struct MainView: View {
var arrayList: [CreateListItems] = []
init() {
let a = CreateListItems(name: "First Name!")
let b = CreateListItems(name: "Second Name!")
let c = CreateListItems(name: "Third Name!")
arrayList.append(a)
arrayList.append(b)
arrayList.append(c)
}
var body: some View {
return VStack {
ZStack {
NavigationView {
List {
ForEach(arrayList) { x in
Text("\(x.name)")
}
}.navigationBarTitle("Main View")
}
}
}
}
}
struct UpdateOtherViewFromHere: View {
func updateList() {
//Code that should remove "FirstName" from the List in MainView
}
var body: some View {
return VStack {
Button(action: {
updateList()
}) {
Image(systemName: "heart.slash")
.font(.largeTitle)
Text("Click Me!")
}
}
}
}
struct CreateListItems: Identifiable {
var id: UUID = UUID()
var name: String
}
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView()
}
}
You can share it using #State and #Binding if you put
struct ContentView: View {
#State var arrayList: [CreateListItems] = []
struct MainView: View {
#Binding var arrayList: [CreateListItems]
struct UpdateOtherViewFromHere: View {
#Binding var arrayList: [CreateListItems]
or you use the MVVM pattern and store the list in an ObservableObject and use #StateObject/#ObservedObject (source) and use #EnvironmentObject(connection) to share it between your Views.
https://developer.apple.com/documentation/swiftui/managing-model-data-in-your-app
class ParentViewModel: ObservableObject{
#Published var arrayList: [CreateListItems] = []
init(){
addSamples()
}
func addSamples() {
let a = CreateListItems(name: "First Name!")
let b = CreateListItems(name: "Second Name!")
let c = CreateListItems(name: "Third Name!")
arrayList.append(a)
arrayList.append(b)
arrayList.append(c)
}
func updateList() {
let a = CreateListItems(name: "\(arrayList.count + 1) Name!")
arrayList.append(a)
}
}
struct ParentView: View {
#StateObject var vm: ParentViewModel = ParentViewModel()
var body: some View {
TabView {
MainView().environmentObject(vm)
.tabItem() {
VStack {
Image(systemName: "circle.fill")
Text("MainView")
}
}.tag(0)
UpdateOtherViewFromHere().environmentObject(vm)
.tabItem() {
VStack {
Image(systemName: "circle.fill")
Text("SecondView")
}
}.tag(1)
}
}
}
struct MainView: View {
#EnvironmentObject var vm: ParentViewModel
var body: some View {
return VStack {
ZStack {
NavigationView {
List {
ForEach(vm.arrayList) { x in
Text(x.name)
}
}.navigationBarTitle("Main View")
}
}
}
}
}
struct UpdateOtherViewFromHere: View {
#EnvironmentObject var vm: ParentViewModel
var body: some View {
return VStack {
Button(action: {
vm.updateList()
}) {
Image(systemName: "heart.slash")
.font(.largeTitle)
Text("Click Me!")
}
}
}
}
Swift 5, iOS 13
I want to use passthroughSubject publisher; but I my gut tells me its a global variable and as such very poor practice. How can make this global variable less global, while still being usable. Here's some code to show what I talking about.
I know there are a dozen other ways to do this, but I wanted to create some simple code to illustrate the issue.
import SwiftUI
import Combine
let switcher = PassthroughSubject<Void,Never>()
struct SwiftUIViewF: View {
#State var nextPage = false
var body: some View {
VStack {
Text("Switcher")
.onReceive(switcher) { (_) in
self.nextPage.toggle()
}
if nextPage {
Page1ViewF()
} else {
Page2ViewF()
}
}
}
}
struct Page1ViewF: View {
var body: some View {
Text("Page 1")
.onTapGesture {
switcher.send()
}
}
}
struct Page2ViewF: View {
var body: some View {
Text("Page 2")
.onTapGesture {
switcher.send()
}
}
}
struct SwiftUIViewF_Previews: PreviewProvider {
static var previews: some View {
SwiftUIViewF()
}
}
Here is possible solution - to hold it in parent and inject into child views:
struct SwiftUIViewF: View {
let switcher = PassthroughSubject<Void,Never>()
#State var nextPage = false
var body: some View {
VStack {
Text("Switcher")
.onReceive(switcher) { (_) in
self.nextPage.toggle()
}
if nextPage {
Page1ViewF(switcher: switcher)
} else {
Page2ViewF(switcher: switcher)
}
}
}
}
struct Page1ViewF: View {
let switcher: PassthroughSubject<Void,Never>
var body: some View {
Text("Page 1")
.onTapGesture {
self.switcher.send()
}
}
}
struct Page2ViewF: View {
let switcher: PassthroughSubject<Void,Never>
var body: some View {
Text("Page 2")
.onTapGesture {
self.switcher.send()
}
}
}
An example using #EnvironmentObject.
Let SDK take care of observing / passing things for you, rather than setting up yourself.
Especially when your usage is a simple toggle.
import SwiftUI
import Combine
final class EnvState: ObservableObject { #Published var nextPage = false }
struct SwiftUIViewF: View {
#EnvironmentObject var env: EnvState
var body: some View {
VStack {
Text("Switcher")
if env.nextPage {
Page1ViewF()
} else {
Page2ViewF()
}
}
}
}
struct Page1ViewF: View {
#EnvironmentObject var env: EnvState
var body: some View {
Text("Page 1")
.onTapGesture {
env.nextPage.toggle()
}
}
}
struct Page2ViewF: View {
#EnvironmentObject var env: EnvState
var body: some View {
Text("Page 2")
.onTapGesture {
env.nextPage.toggle()
}
}
}
struct SwiftUIViewF_Previews: PreviewProvider {
static var previews: some View {
SwiftUIViewF().environmentObject(EnvState())
}
}