If i display the same custom view in ContentView everthing is fine, but displaying in a modal .sheet() view causes attributeGraph cycle errors. If i comment out the call in the ContentView, the problem remains. This does not affect apps behaviour, so far. I suggest that the LazyVGrid makes in modal situations via .sheet() trouble. Is there any work around?
xcode version 13.4.1 and macOS (12.4) target
struct ContentView: View {
#State private var dialogSimple = false
var buttons: some View {
HStack {
Button("simple") {
dialogSimple = true
}
.sheet(isPresented: $dialogSimple) {
DialogSimple() // with Graph cycle error !
}
}
.padding(.all)
}
var body: some View {
VStack {
DataView() // without Graph cycle error !
buttons
Text("Test Dialog via .sheet() shows error:")
Text("AttributeGraph: cycle detected through attribute ...")
}
.padding(.all)
.font(.headline)
}
}
struct DialogSimple: View {
#Environment(\.presentationMode) var presentationMode
var body: some View {
VStack {
DataView()
Button("Close") {
self.presentationMode.wrappedValue.dismiss()
}
.padding(.all)
}
}
}
struct DataView: View {
var columns: [GridItem] = Array(repeating: .init(.flexible()), count: 2)
var body: some View {
LazyVGrid(columns: columns) {
Text("Field 1")
Text("Value1")
Text("Field 2")
Text("Value2")
}.frame(width: 300.0).font(.body)
}
}
Related
In my app I add/remove a subview to/from a TabView based on some condition. I'd like to animate tab item addition/removal in tab bar. My experiment (see code below) shows it's not working. I read on the net that TabView support for animation is quite limited and some people rolled their own implementation. But just in case, is it possible to implement it?
import SwiftUI
struct ContentView: View {
#State var showBoth: Bool = false
var body: some View {
TabView {
Button("Test") {
withAnimation {
showBoth.toggle()
}
}
.tabItem {
Label("1", systemImage: "1.circle")
}
if showBoth {
Text("2")
.tabItem {
Label("2", systemImage: "2.circle")
}
.transition(.slide)
}
}
}
}
Note: moving transition() call to the Label passed to tabItem() doesn't work either.
As commented Apple wants the TabBar to stay unchanged throughout the App.
But you can simply implement your own Tabbar with full control:
struct ContentView: View {
#State private var currentTab = "One"
#State var showBoth: Bool = false
var body: some View {
VStack {
TabView(selection: $currentTab) {
// Tab 1.
VStack {
Button("Toggle 2. Tab") {
withAnimation {
showBoth.toggle()
}
}
} .tag("One")
// Tab 2.
VStack {
Text("Two")
} .tag("Two")
}
// custom Tabbar buttons
Divider()
HStack {
OwnTabBarButton("One", imageName: "1.circle")
if showBoth {
OwnTabBarButton("Two", imageName: "2.circle")
.transition(.scale)
}
}
}
}
func OwnTabBarButton(_ label: String, imageName: String) -> some View {
Button {
currentTab = label
} label: {
VStack {
Image(systemName: imageName)
Text(label)
}
}
.padding([.horizontal,.top])
}
}
In a multiplatform app I'm showing a sheet to collect a small amount of user input. On iOS, when the sheet is dismissed, the relevant .onDismiss method is called but not on macOS.
I've read that having the .onDismiss in the List can cause problems so I've attached it to the button itself with no improvement. I've also tried passing the isPresented binding through and toggling that within the sheet itself to dismiss, but again with no success.
I am employing a NavigationView but removing that makes no difference. The following simplified example demonstrates my problem. Any ideas? Should I even be using a sheet for this purpose on macOS?
I just want to make clear that I have no problem closing the sheet. The other questions I found were regarding problems closing the sheet - I can do that fine.
import SwiftUI
#main
struct SheetTestApp: App {
var body: some Scene {
WindowGroup {
ContentView()
}
}
}
struct ContentView: View {
var body: some View {
NavigationView {
ListView()
}
}
}
The List view.
struct ListView: View {
#State private var isPresented: Bool = false
var body: some View {
VStack {
Text("Patterns").font(.title)
Button(action: {
isPresented = true
}, label: {
Text("Add")
})
.sheet(isPresented: $isPresented, onDismiss: {
doSomethingAfter()
}) {
TestSheetView()
}
List {
Text("Bingo")
Text("Bongo")
Text("Banjo")
}
.onAppear(perform: {
doSomethingBefore()
})
}
}
func doSomethingBefore() {
print("Johnny")
}
func doSomethingAfter() {
print("Cash")
}
}
This is the sheet view.
struct TestSheetView: View {
#Environment(\.presentationMode) var presentationMode
#State private var name = ""
var body: some View {
Form {
TextField("Enter name", text: $name)
.padding()
HStack {
Spacer()
Button("Save") {
presentationMode.wrappedValue.dismiss()
}
Spacer()
}
}
.frame(minWidth: 300, minHeight: 300)
.navigationTitle("Jedward")
}
}
Bad issue.. you are right. OnDismiss is not called. Here is a workaround with Proxybinding
var body: some View {
VStack {
Text("Patterns").font(.title)
Button(action: {
isPresented = true
}, label: {
Text("Add")
})
List {
Text("Bingo")
Text("Bongo")
Text("Banjo")
}
.onAppear(perform: {
doSomethingBefore()
})
}
.sheet(isPresented: Binding<Bool>(
get: {
isPresented
}, set: {
isPresented = $0
if !$0 {
doSomethingAfter()
}
})) {
TestSheetView()
}
}
this is a Macos app where the parsclass is setup in a previous view that contains the YardageRowView below. That previous view is responsible for changing the contents of the parsclass. This is working is other views that use a NavigationLink to display the views.
When the parsclass is changed, this view is refreshed, but the previous value is put in the text field on the holeValueTestView.
I cannot comprehend how the value is not being passed into the holeValueTestView correctly
This is a view shown as a .sheet, and if I dismiss it and display it again, everything is fine.
if you create a macOS project called YardageSample and replace the ContentView.swift and YardageSampleApp.swift with the two files below, you can see that the display in red changes and the black numbers do not change until you click Done and redisplay the .sheet
//
// YardageSampleApp.swift
// YardageSample
//
// Created by Brian Quick on 2021-04-12.
//
import SwiftUI
#main
struct YardageSampleApp: App {
#StateObject var parsclass = parsClass()
var body: some Scene {
WindowGroup {
ContentView()
.environmentObject(parsclass)
}
}
}
//
// ContentView.swift
// YardageSample
//
// Created by Brian Quick on 2021-04-12.
//
import SwiftUI
struct ContentView: View {
#StateObject var parsclass = parsClass()
enum ActiveSheet : String , Identifiable {
case CourseMaintenance
var id: String {
return self.rawValue
}
}
#State var activeSheet : ActiveSheet? = nil
var body: some View {
Button(action: {
self.activeSheet = .CourseMaintenance
}) {
Text("Course Maintenance")
}
.sheet(item: $activeSheet) { sheet in
switch sheet {
case .CourseMaintenance:
CourseMaintenance()
}
}.frame(width: 200, height: 200, alignment: /*#START_MENU_TOKEN#*/.center/*#END_MENU_TOKEN#*/)
}
}
class parsClass: ObservableObject {
#Published var pars = [parsRec]()
init() {
self.pars = [parsRec]()
self.pars.append(parsRec())
}
func create(newpars: [parsRec]) {
pars.removeAll()
pars = newpars
}
}
class parsRec: Identifiable, Codable {
var id = UUID()
var Hole = 1
var Yardage = 1
}
struct CourseMaintenance: View {
#EnvironmentObject var parsclass: parsClass
#Environment(\.presentationMode) var presentationMode
var body: some View {
VStack {
Button(action: {presentationMode.wrappedValue.dismiss()}, label: {
Text("Done")
})
Button(action: {switchScores(number: 1)}, label: {
Text("Button 1")
})
Button(action: {switchScores(number: 2)}, label: {
Text("Button 2")
})
Button(action: {switchScores(number: 3)}, label: {
Text("Button 3")
})
CourseDetail().environmentObject(parsclass)
}.frame(width: 400, height: 400, alignment: .center)
}
func switchScores(number: Int) {
var newparRecs = [parsRec]()
for i in 0..<17 {
let myrec = parsRec()
myrec.Hole = i
myrec.Yardage = number
newparRecs.append(myrec)
}
parsclass.create(newpars: newparRecs)
}
}
struct CourseDetail: View {
#EnvironmentObject var parsclass: parsClass
var body: some View {
HStack(spacing: 0) {
ForEach(parsclass.pars.indices, id: \.self) { indice in
// this displays the previous value
holeValueTestView(value: String(parsclass.pars[indice].Yardage))
// this displays the correct value after parsclass has changed
Text(String(parsclass.pars[indice].Yardage))
.foregroundColor(.red)
}
}
}
}
struct holeValueTestView: View {
#State var value: String
var body: some View {
//TextField(String(value), text: $value)
Text(value)
}
}
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView()
}
}
There are a couple of issues going on:
You have multiple instances of parsClass. One is defined in YardageSampleApp and passed into the view hierarchy as a #EnvironmentObject. The second is defined in ContentView as a #StateObject. Make sure you're only using one.
On holeValueTestView, you defined value as a #State variable. That gets set initially when the view is created by its parent and then it maintains its own state. So, when the environmentObject changed, because it was in charge of its own state at this point, it didn't update the value. You can simply remove #State and see the behavior that you want.
struct ContentView: View {
#EnvironmentObject var parsclass : parsClass //<-- Here
enum ActiveSheet : String , Identifiable {
case CourseMaintenance
var id: String {
return self.rawValue
}
}
#State var activeSheet : ActiveSheet? = nil
var body: some View {
Button(action: {
self.activeSheet = .CourseMaintenance
}) {
Text("Course Maintenance")
}
.sheet(item: $activeSheet) { sheet in
switch sheet {
case .CourseMaintenance:
CourseMaintenance()
}
}.frame(width: 200, height: 200, alignment: .center)
}
}
struct holeValueTestView: View {
var value: String //<-- Here
var body: some View {
Text(value)
}
}
As a side note:
In Swift, normally type names are capitalized. If you want to write idiomatic Swift, you would change your parsClass to ParsClass for example.
In this simple example app, I have the following requirements:
have multiple windows, each having it's own ViewModel
toggling the Toggle in one window should not update the other window's
I want to also be able to toggle via menu
As it is right now, the first two points are not given, the last point works though. I do already know that when I move the ViewModel's single source of truth to the ContentView works for the first two points, but then I wouldn't have access at the WindowGroup level, where I inject the commands.
import SwiftUI
#main
struct ViewModelAndCommandsApp: App {
var body: some Scene {
ContentScene()
}
}
class ViewModel: ObservableObject {
#Published var toggleState = true
}
struct ContentScene: Scene {
#StateObject private var vm = ViewModel()// injecting here fulfills the last point only…
var body: some Scene {
WindowGroup {
ContentView()
.environmentObject(vm)
.frame(width: 200, height: 200)
}
.commands {
ContentCommands(vm: vm)
}
}
}
struct ContentCommands: Commands {
#ObservedObject var vm: ViewModel
var body: some Commands {
CommandGroup(before: .toolbar) {
Button("Toggle Some State") {
vm.toggleState.toggle()
}
}
}
}
struct ContentView: View {
#EnvironmentObject var vm: ViewModel//injecting here will result in window independant ViewModels, but make them unavailable in `ContactScene` and `ContentCommands`…
var body: some View {
Toggle(isOn: $vm.toggleState, label: {
Text("Some State")
})
}
}
How can I fulfill theses requirements–is there a SwiftUI solution to this or will I have to implement a SceneDelegate (is this the solution anyway?)?
Edit:
To be more specific: I'd like to know how I can go about instantiating a ViewModel for each individual scene and also be able to know from the menu bar which ViewModel is meant to be changed.
Long story short, see the code below. The project is called WindowSample this needs to match your app name in the URL registration.
import SwiftUI
#main
struct WindowSampleApp: App {
var body: some Scene {
ContentScene()
}
}
//This can be done several different ways. You just
//need somewhere to store multiple copies of the VM
class AStoragePlace {
private static var viewModels: [ViewModel] = []
static func getAViewModel(id: String?) -> ViewModel? {
var result: ViewModel? = nil
if id != nil{
result = viewModels.filter({$0.id == id}).first
if result == nil{
let newVm = ViewModel(id: id!)
viewModels.append(newVm)
result = newVm
}
}
return result
}
}
struct ContentCommands: Commands {
#ObservedObject var vm: ViewModel
var body: some Commands {
CommandGroup(before: .toolbar) {
Button("Toggle Some State \(vm.id)") {
vm.testMenu()
}
}
}
}
class ViewModel: ObservableObject, Identifiable {
let id: String
#Published var toggleState = true
init(id: String) {
self.id = id
}
func testMenu() {
toggleState.toggle()
}
}
struct ContentScene: Scene {
var body: some Scene {
//Trying to init from 1 windowGroup only makes a copy not a new scene
WindowGroup("1") {
ToggleView(vm: AStoragePlace.getAViewModel(id: "1")!)
.frame(width: 200, height: 200)
}
.commands {
ContentCommands(vm: AStoragePlace.getAViewModel(id: "1")!)
}.handlesExternalEvents(matching: Set(arrayLiteral: "1"))
//To open this go to File>New>New 2 Window
WindowGroup("2") {
ToggleView(vm: AStoragePlace.getAViewModel(id: "2")!)
.frame(width: 200, height: 200)
}
.commands {
ContentCommands(vm: AStoragePlace.getAViewModel(id: "2")!)
}.handlesExternalEvents(matching: Set(arrayLiteral: "2"))
}
}
struct ToggleView: View {
#Environment(\.openURL) var openURL
#ObservedObject var vm: ViewModel
var body: some View {
VStack{
//Makes copies of the window/scene
Button("new-window-of type \(vm.id)", action: {
//appname needs to be a registered url in info.plist
//Info Property List>Url types>url scheme>item 0 == appname
//Info Property List>Url types>url identifier == appname
if let url = URL(string: "WindowSample://\(vm.id)") {
openURL(url)
}
})
//Toggle the state
Toggle(isOn: $vm.toggleState, label: {
Text("Some State \(vm.id)")
})
}
}
}
How can I transition from one View to another? Is there push / pop like in UIKit? Do I have to use a NavigationView and if so how?
Using a NavigationView
NavigationViews are tied to NavigationButton (AFAIK that is the only way to trigger a segue). Here is a simple example where the main view can transition to a detail view.
struct DetailView : View {
let value: String
var body : some View {
Text("Full View: \(value)")
}
}
struct MainView : View {
var body : some View {
NavigationView {
NavigationButton(destination: DetailView(value: "Hello World"),
label: { Text("Click Me") })
}
}
}
This will automatically handle transitions and add a back button.
Using State
Another approach is to use a stateful variable to determine if the child view is displayed. Here is another simple example:
struct DetailView : View {
let value: String
let onDone: () -> Void
var body : some View {
VStack {
Text("Full View: \(value)")
Button(action: onDone, label: { Text("Back") })
}
}
}
struct MainView : View {
#State var displaySubview = false
var body : some View {
VStack {
if displaySubview {
DetailView(value: "Hello World") {
self.displaySubview = false
}
} else {
Button(action: {
self.displaySubview = true
}, label: { Text("Click Me") })
}
}
}
}
This approach requires you to implement more of the UI elements, but it also allows for more control over views.
It works for me
struct ContentView : View {
var body : some View {
NavigationView {
NavigationLink(destination: DetailView(), label: { Text("To Detail")})
}
}}