Here is the code fragment from Apple Document
#main
struct MyApp: App {
var body: some Scene {
WindowGroup {
ContentView()
}
#if os(macOS)
Settings {
SettingsView()
}
#endif
}
}
I followed the document to watch the scenePhase like this but got nothing
struct MyScene: Scene {
#Environment(\.scenePhase) private var scenePhase
var body: some Scene {
Settings {
SettingView()
}
.onChange(of: scenePhase) { newValue in
print(newValue)
}
}
}
I think that is because that scenePhase is the scenePhase of MyApp's Scene. But how to get the scenePhase of Settings? Or how to detect SettingView's on disappear?
Codes below are not working.
struct SettingView: View {
#Environment(\.scenePhase) private var scenePhase
var body: some View {
SomeView()
.onAppear(perform: {
print("setting view on appear") // only print once
})
.onDisappear {
print("on disappear") // never print
}
.onChange(of: scenePhase) { newValue in
print(newValue) // only print once
}
}
}
Related
I have a settings view that has a button which toggles a binding that's stored with UserDefaults.
struct Settings: View {
#ObservedObject var settingsVM = SetttingsViewModel()
var body: some View {
if settingsVM.settingActivated {
Text("Setting activated")
} else {
Text("Setting deactivated")
}
Button("Activate") {
settingsVM.settingActivated.toggle()
}
}
}
SettingsViewModel
class SetttingsViewModel: ObservableObject {
#Published var settingActivated: Bool = UserDefaults.standard.bool(forKey: "settingActivated") {
didSet {
UserDefaults.standard.set(self.settingActivated, forKey: "settingActivated")
}
}
}
The text("Setting activated/ Setting deactivated")in the Settings view update instantly when i press the button but the text in ContentView doesn't change unless i restart the app & i have no idea why.
struct ContentView: View {
#ObservedObject var settingsVM = SetttingsViewModel()
#State private var showsettings = false
var body: some View {
if settingsVM.settingActivated {
Text("Setting Activated")
.padding(.top)
} else {
Text("Setting Deactivated")
.padding(.top)
}
Button("Show Settings") {
showsettings.toggle()
}
.sheet(isPresented: $showsettings) {
Settings()
}
.frame(width: 300, height: 300)
}
}
This is for a macOS 10.15 app so i can't use #AppStorage
Right now, you don't have any code in you view model to react to a change in UserDefaults. Meaning, if UserDefaults gets a new value set, it won't know about it. And, since you're using a different instance of SettingsViewModel in your two different views, they can easily become out-of-sync.
The easiest change would be to pass the same instance of SettingsViewModel to Settings:
struct Settings: View {
#ObservedObject var settingsVM: SettingsViewModel //<-- Here
var body: some View {
if settingsVM.settingActivated {
Text("Setting activated")
} else {
Text("Setting deactivated")
}
Button("Activate") {
settingsVM.settingActivated.toggle()
}
}
}
struct ContentView: View {
#ObservedObject var settingsVM = SetttingsViewModel()
#State private var showsettings = false
var body: some View {
if settingsVM.settingActivated {
Text("Setting Activated")
.padding(.top)
} else {
Text("Setting Deactivated")
.padding(.top)
}
Button("Show Settings") {
showsettings.toggle()
}
.sheet(isPresented: $showsettings) {
Settings(settingsVM: settingsVM) //<-- Here
}
.frame(width: 300, height: 300)
}
}
Another option would be to use a custom property wrapper (like AppStorage, but available to earlier targets): https://xavierlowmiller.github.io/blog/2020/09/04/iOS-13-AppStorage
Also, #vadian's comment is important -- if you had access to it, you'd want to use #StateObject. But, since you don't, it's important to store your ObservableObject at the top level so it doesn't get recreated.
For some reason, I'm not getting the .onChange(scenePhase) firing. No matter which View I place the modifier on there's no output:
import SwiftUI
struct TabViewDashboard: View {
#Environment(\.scenePhase) var scenePhase
var body: some View {
ZStack {
VStack {
//more code here....
}
.onChange(of: scenePhase) { newPhase in
debugPrint("NewPhase: ", newPhase as Any)
}
.onAppear {
// code here
}
.onDisappear {
// function here
}
}
}
I'm not getting any debug output for any scene changes.
I know this View is being called from a UIKit->SwiftUI UIHostingController. Could this be the reason I'm getting no output?
Min. OS: iOS 14.
How can I display an alert dialog box from a menu item for MacOS apps using SwiftUI?
The usual code which works for iOS #State var isOn = false and .alert("title", isPresented: isOn) {..} doesn't work.
#main
struct MyApp: App {
var body: some Scene {
WindowGroup {
ContentView()
}.commands {
CommandMenu("Test menu") {
Button(action: {
// I want to show an alert dialog dialog here.
}) {
Text("Click Me")
}
}
}
}
The usual code works fine. You would never try to stuff an Alert inside of a Button. You wouldn't do it here.
#main
struct MyApp: App {
#State var isOn = false
var body: some Scene {
WindowGroup {
NavigationView {
ContentView()
.alert("title", isPresented: $isOn) {
Button("OK", role: .cancel) { }
}
}
}.commands {
CommandMenu("Test menu") {
Button(action: {
isOn = true
}) {
Text("Click Me")
}
}
}
}
}
Does someone know how to connect commands to the rest of the project?
For example: I want to toggle the AddNew variable in the content view to show the add new item sheet by using the command.
struct SampleApp: App {
var body: some Scene {
WindowGroup {
ContentView()
}
.commands {
CommandGroup(after: CommandGroupPlacement.newItem) {
Button("Add new", action: {
self.AddNew.toggle() // should toggle variable in content View
})
}
}
}
}
struct ContentView: View {
#State var AddNew = false
var body: some View {
Button(action: {
self.AddNew.toggle()
}) {
Text("Show Detail")
}.sheet(isPresented: $AddNew) {
AddNew(dimiss: $AddNew)
}
}
}
A solution could be to have a #Published var in a class conforming to ObservableObject.
You would toggle the boolean in the class and access it from wherever you want (as an #EnvironmentObject for example).
Like this:
class AppModel: ObservableObject {
#Published var addNew: Bool = false
}
struct SampleApp: App {
#ObservedObject var model = AppModel()
var body: some Scene {
WindowGroup {
ContentView()
.environmentObject(model)
}
.commands {
CommandGroup(after: CommandGroupPlacement.newItem) {
Button("Add new", action: {
self.model.addNew.toggle()
})
}
}
}
}
struct ContentView: View {
#EnvironmentObject var model: AppModel
var body: some View {
Button(action: {
self.model.addNew.toggle()
}) {
Text("Show Detail")
}.sheet(isPresented: $model.addNew) {
AddNew(dimiss: $model.addNew)
}
}
}
Consider the following code:
class ApplicationHostingView: ObservableObject {
#Published var value: Bool
}
struct ApplicationHostingView: View {
// view model env obj
var body: some View {
Group {
if applicationHostingViewModel.value {
LoginView()
.transition(.move(edge: .leading)) // <<<< Transition for Login View
} else {
IntroView()
}
}
}
}
struct IntroView: View {
// view model env obj
var body: some View {
Button(action: { applicationHostingViewModel.value = true }) {
Text("Continue")
}
}
}
struct LoginView: View {
var body: some View {
Text("Hello World")
}
}
ISSUE
In this case, I see my transition from IntroView to LoginView work fine except for any of the animations. Animations inside IntroView based on the conditionals seem to be working fine but transitions that change the entire screen don't seem to work.
change group to ZStack
add animation somewhere.
class ApplicationHostingViewModel: ObservableObject {
#Published var value: Bool = false
}
struct ApplicationHostingView: View {
// view model env obj
#ObservedObject var applicationHostingViewModel : ApplicationHostingViewModel
var body: some View {
ZStack {
if applicationHostingViewModel.value {
LoginView()
.transition(.move(edge: .leading))
} else {
IntroView(applicationHostingViewModel:applicationHostingViewModel)
}
}
}
}
struct IntroView: View {
// view model env obj
#ObservedObject var applicationHostingViewModel : ApplicationHostingViewModel
var body: some View {
Button(action: {
withAnimation(.default){
self.applicationHostingViewModel.value = true} }) {
Text("Continue")
}
}
}
struct LoginView: View {
var body: some View {
Text("Hello World").frame(maxWidth: .infinity, maxHeight: .infinity)
}
}