Post not yet marked as solved
Hi guys,
I am trying to use the new @Observable macro. According to the documentation, this new macro will automatically generate observable properties, but I am having issues using my properties when Bindings are necessary.
Previously I had a setup like this:
class Example: ObservableObject {
@Published public var myArray = [CustomType]()
}
I initialised one instance of the Example-class in @main
@StateObject private var exampleClass = Example()
And added as an .environmentObject onto the root view
ContentView()
.environmentObject(exampleClass)
In child views I was able to access the @Published property as a binding via
@EnvironmentObject private var example: Example
$example.myArray
What I am trying now
This is the setup that I am trying with now:
@Observable class Example {
public var myArray = [CustomType]()
}
State instead of StateObject in @main
@State private var exampleClass = Example()
.environment instead of .environmentObject
ContentView()
.environmentObject(exampleClass)
@Environment instead of @EnvironmentObject
@Environment(Example.self) private var example
This new setup is not letting me access $example.myArray. Is this intended? Could someone explain why?
Post not yet marked as solved
I am following this Apple Article on how to setup an AVPlayer. The only difference is I am using @Observable instead of an ObservableObject with @Published vars.
Using @Observable results in the following error: Cannot find '$isPlaying' in scope
If I remove the "$" symbol I get a bit more insight:
Cannot convert value of type 'Bool' to expected argument type 'Published<Bool>.Publisher'
If I change by class to an OO, it works fine, although, is there anyway to get this to work with @Observable?
Post not yet marked as solved
Following this Apple Article, I copied their code over for observePlayingState().
The only difference I am using @Observable instead of ObservableObject and @Published for var isPlaying.
We get a bit more insight after removing the $ symbol, leading to a more telling error of: Cannot convert value of type 'Bool' to expected argument type 'Published.Publisher'
Is there anyway to get this working with @Observable?
Post not yet marked as solved
Not sure if this code is supposed to leak memory or am I missing something?
import SwiftUI
import Observation
@Observable class SheetViewModel {
let color: Color = Color.red
init() { print("init") }
deinit { print("deinit") }
}
struct SheetView: View {
@State var viewModel = SheetViewModel()
var body: some View {
Color(viewModel.color)
}
}
@main
struct ObservableMemoryLeakApp: App {
@State var presented: Bool = false
var body: some Scene {
WindowGroup {
Button("Show") {
presented = true
}
.sheet(isPresented: $presented) {
SheetView()
}
}
}
}
Every time the sheet is presented/dismissed, a new SheetViewModel is created (init is printed) but it never released (deinit not printed). Also, all previously created SheetViewModel instances are visible in Memory Graph and have "Leaked allocation" badge.
Reverting to ObservableObject/@StateObject fixes the issue, deinit is called every time the sheet is dismissed:
-import Observation
-@Observable class SheetViewModel {
+class SheetViewModel: ObservableObject {
- @State var viewModel = SheetViewModel()
+ @StateObject var viewModel = SheetViewModel()
Does this mean there's a bug in Observation framework?
Reported as FB13015569.
Post not yet marked as solved
In my test app I have two squares (red and green) that change their size when I click a toggle button. I use two different approaches to change the scale. The red square is scaled using the .visualEffect modifier and the green square is scaled using the .scaleEffect modifier. When I click the button the first time, both squares change size. But when I click again and again, only the green square changes its size. The red square stays the same after the first change. Self._printChanges() show that both views get changes each time. What am I doing wrong? Or is this a bug?
import SwiftUI
import Observation
struct ContentView: View {
@State private var model: Model = Model()
var body: some View {
VStack {
HStack {
RedSquareView()
GreenSquareView()
}
.environment(model)
Button {
model.scaled.toggle()
} label: {
Text("Toggle scale")
}
}
.padding()
}
}
struct RedSquareView: View {
@Environment(Model.self) var model
var body: some View {
let _ = Self._printChanges()
Rectangle()
.fill(Color.red)
.frame(width: 100, height: 100)
.visualEffect { content, geometryProxy in
content.scaleEffect(model.scaled ? 0.5 : 1.0, anchor: .center)
}
.animation(.bouncy, value: model.scaled)
}
}
struct GreenSquareView: View {
@Environment(Model.self) var model
var body: some View {
let _ = Self._printChanges()
Rectangle()
.fill(Color.green)
.frame(width: 100, height: 100)
.scaleEffect(model.scaled ? 0.5 : 1.0, anchor: .center)
.animation(.bouncy, value: model.scaled)
}
}
@Observable
final class Model: Sendable {
var scaled: Bool = false
}
#Preview {
ContentView()
}
Post not yet marked as solved
I've encountered a problem which I don't know if is related to swiftui, the observation framework, or both
If I run the following code I have two tabs, with the second tab that use a "lazy model" which is deallocated each time disappears (this is necessary for my use case)
If I switch to the second tab, all works right. If I return to the first tab, the onDisappear on the foo view should force the "Bar" variable to nil , because the FooView may be still allocated (it is a tab bar) but that resource should be released
If that bar variable is set to nil, the MyBar should be replaced by the ProgressView in the "background"
I expect regarding that the Bar that:
the instance is nil on Foo
no other view should be shown with that instance (MyBar is now disappeared)
Because no ref, the Bar observable object should be now deallocated
In reality the Bar object is still in my memory graph
Any suggestions? is it a bug?
@Observable
class Bar {
var hello: String = ""
}
struct Foo: View {
@State
var bar: Bar?
@ViewBuilder
private var content: some View {
if let bar {
MyBar(bar: bar)
} else {
ProgressView()
}
}
var body: some View {
content
.onAppear {
bar = Bar()
}
.onDisappear {
self.bar = nil
}
}
}
struct MyBar: View {
@Bindable
var bar: Bar
var body: some View {
Text("MyBar")
}
}
struct ContentView: View {
@State
var tag: Int = 0
var body: some View {
TabView(selection: $tag) {
Text("First")
.tag(0)
.tabItem {
Text("First")
}
Foo()
.tag(1)
.tabItem {
Text("Foo")
}
}
}
}
Post not yet marked as solved
I'm working on a SwiftUI app using SwiftData for state management. I've encountered an issue with view updates when mutating a model. Here's a minimal example to illustrate the problem:
import SwiftUI
import SwiftData
// MARK: - Models
@Model
class A {
@Relationship var bs: [B] = [B]()
init(bs: [B]) {
self.bs = bs
}
}
@Model
class B {
@Relationship var cs: [C] = [C]()
init(cs: [C]) {
self.cs = cs
}
}
@Model
class C {
var done: Bool
init(done: Bool) {
self.done = done
}
}
// MARK: - Views
struct CView: View {
var c: C
var body: some View {
@Bindable var c = c
HStack {
Toggle(isOn: $c.done, label: {
Text("Done")
})
}
}
}
struct BView: View {
var b: B
var body: some View {
List(b.cs) { c in
CView(c: c)
}
}
}
struct AView: View {
var a: A
var body: some View {
List(a.bs) { b in
NavigationLink {
BView(b: b)
} label: {
Text("B \(b.cs.allSatisfy({ $0.done }).description)")
}
}
}
}
struct ContentView: View {
@Query private var aList: [A]
var body: some View {
NavigationStack {
List(aList) { a in
NavigationLink {
AView(a: a)
} label: {
Text("A \(a.bs.allSatisfy({ $0.cs.allSatisfy({ $0.done }) }).description)")
}
}
}
}
}
@main
struct Minimal: App {
var body: some Scene {
WindowGroup {
ContentView()
}
}
}
#Preview {
let config = ModelConfiguration(isStoredInMemoryOnly: true)
let container = try! ModelContainer(for: A.self, configurations: config)
var c = C(done: false)
container.mainContext.insert(c)
var b = B(cs: [c])
container.mainContext.insert(b)
var a = A(bs: [b])
container.mainContext.insert(a)
return ContentView()
.modelContainer(container)
}
In this setup, I have a CView where I toggle the state of a model C. After toggling C and navigating back, the grandparent view AView does not reflect the updated state (it still shows false instead of true). However, if I navigate back to the root ContentView and then go to AView, the status is updated correctly.
Why doesn't AView update immediately after mutating C in CView, but updates correctly when navigating back to the root ContentView? I expected the grandparent view to reflect the changes immediately as per SwiftData's observation mechanism.
Post not yet marked as solved
Hello,
my goal is it to implement an Edit Sheet of a Model with Discard changes in SwiftData.
Xcode Version 15.0 beta 6 (15A5219j)
Approaches
In the following modelContext refers to the context fetched from the environment by the View. Also code for showing the sheet (eg. toggling isPresented) is omitted.
// App
ContentView()
.modelContainer(for: Model.self, isAutosaveEnabled: true, isUndoEnabled: true)
// In Content View
@Query var models: [Model]
//...
ForEach(models) { model in
ModelView(model: model)
//eg. longpresgesture that calls openEditSheet
.sheet(..., content: {
EditModelView(model: model)
}
}
Disabling autosave + rollback
// In ContentView
func openEditSheet() {
modelContext.autosaveEnabled = false
}
// In EditModelView
func discardEditSheet() {
modelContext.rollback()
modelContext.autosaveEnabled = true
}
func saveEditSheet() {
try? modelContext.save() // probably not needed if autosave gets enabled anyway
modelContext.autosaveEnabled = true
}
However this approach does not work, as SwiftData continues to save anyway and therefore there is nothing to rollback.
modelContext in Memory
// In ContentView
let context = ModelContext(modelContext.container)
context.autosaveEnabled = false
context.container.configuration.removeAll()
context.container.configuration.insert(ModelConfiguration(..., inMemory: true)
//...
EditModelView()
.modelContext(context)
// Also tried: .enviroment(\.modelContext, context)
// In EditModelView
func discardEditSheet() {
modelContext.rollback() // probably not needed as the container is never saved
}
func saveEditSheet() {
try? modelContext.save() // move to persistent storage from memory
}
The idea was to use something like parent in CoreData. However as this is (currently) not supported.
Also tried this by modifying the modelContext directly (instead of creating a new context) and its container directly or before creating the context.
The child can not be a ModelContainer as you can not pass a context to it or set its mainContext (get-only).
However this approach does not work, as the container does not seem to stay in memory. Maybe related to previous.
BackingData
EditModelView(model: Model(backingData: model.persistentBackingData)
not sure about this one, played around a little with it but not sure what it means / should mean and how I would expect it to work. I have never been great at cooking :).
UndoManager (preferred)
// In ContentView
func openEditSheet() {
modelContext.undoManager?.beginUndoGrouping()
}
// In EditModelView
func discardEditSheet() {
modelContext.undoManager?.endUndoGrouping()
modelContext.undoManager?.undoNestedGroup()
// Also tried adding: try? modelContext.save()
}
func saveEditSheet() {
modelContext.undoManager?.endUndoGrouping()
}
This approach does works kinda weird:
The ModelView of the updated model in ContentView's ForEach is not updated regarding the undo action.
However when I re-open the EditTaskView of the updated model it has the expected state, even though the model to edit is passed by the ContentView (which does not have the correct state?).
After relaunching the app or when modifying the model again (this time not undoing) the previous sate changes are recognised
Therefore this looks like it does what I want, with the ContentView having the correct state, but not displaying it. Only reason I can think of is the Model: Observable not getting triggered and therefore no View update.
Conclusion
After playing around with the above approaches and combining them in every possible way, i think that:
disabling autosave at runtime is currently not working and this is a bug (otherwise autosaveEnabled should be get-only).
UndoManager does not trigger a View update of a Model/Observable and this is a bug
Would be happy to hear other opinions on this. Am I missing something here? Am I ******?
Question
However as my conclusion does not fix my problem I am wondering:
Are my approaches (theoretically) correct?
How do I fix / workaround the UndoManager issue? If I identified it correctly, how can I manually notify the view that a Observable model has changed?
Post not yet marked as solved
class PostManager: ObservableObject {
static let shared = PostManager()
private init() {}
@Published var containers: [PostContainer] = []
// Other code
}
class PostContainer: ObservableObject {
var id: UUID = UUID()
var timestamp: Date
var subreddit: String
var posts: [Post]
var type: ContainerType
var active: Bool
// Init
}
@Model
final class Post: Decodable, ObservableObject {
// Other code
}
In my main view, a network request is made and a PostContainer is created if it doesn't exist. This code works fine, and the view is updated correctly.
let container = PostContainer(timestamp: Date(), subreddit: subreddit, posts: posts, type: .search, active: true)
self.containers.append(container)
If the user wants to see more, they press a button and another request is made. This time, the new data will be added to the PostContainer instead of creating a new one.
if let container = self.containers.first(where: {$0.subreddit == subreddit}) {
// Update previous container
container.timestamp = Date()
print(container.posts.count)
// Map IDs from container and then remove duplicates
let existingIDs = Set(container.posts.map { $0.id })
let filtered = posts.filter { !existingIDs.contains($0.id) }
// Append new post
container.posts.append(contentsOf: filtered)
container.active = true
}
This code is working fine as well, except for the view is not updating. In the view, PostManager is an @EnvironmentObject. I also have a computed variable to get the post and sort them. I added a print statement to that variable and saw that it wasn't being printed even though more data was being added to the PostContainer. At one point, I created an ID for the List that displays the data and had the code inside PostManager update that ID when it was finished. This of course worked, but it's not ideal.
How can I get the view to update when post are appended inside of PostContainer?
Post not yet marked as solved
Our app has an architecture based on ViewModels.
Currently, we are working on migrating from the ObservableObject protocol to the Observable macro (iOS 17+).
The official docs about this are available here: https://developer.apple.com/documentation/swiftui/migrating-from-the-observable-object-protocol-to-the-observable-macro
Our ViewModels that were previously annotated with @StateObject now use just @State, as recommended in the official docs.
Some of our screens (a screen is a SwiftUI view with a corresponding ViewModel) are presented modally. We expect that after dismissing a SwiftUI view that was presented modally, its corresponding ViewModel, which is owned by this view (via the @State modifier), will be deinitialized. However, it seems there is a memory leak, as the ViewModel is not deinitialized after a modal view is dismissed.
Here's a simple code where ModalView is presented modally (through the .sheet modifier), and ModalViewModel, which is a @State of ModalView, is never deinitialized.
import SwiftUI
import Observation
@Observable
final class ModalViewModel {
init() {
print("Simple ViewModel Inited")
}
deinit {
print("Simple ViewModel Deinited") // never called
}
}
struct ModalView: View {
@State var viewModel: ModalViewModel = ModalViewModel()
let closeButtonClosure: () -> Void
var body: some View {
ZStack {
Color.yellow
.ignoresSafeArea()
Button("Close") {
closeButtonClosure()
}
}
}
}
struct ContentView: View {
@State var presentSheet: Bool = false
var body: some View {
Button("Present sheet modally") {
self.presentSheet = true
}
.sheet(isPresented: $presentSheet) {
ModalView {
self.presentSheet = false
}
}
}
}
#Preview {
ContentView()
}
Is this a bug in the iOS 17 beta version or intended behavior? Is it possible to build a relationship between the View and ViewModel in a way where the ViewModel will be deinitialized after the View is dismissed?
Thank you in advance for the help.
Post not yet marked as solved
Since iOS/iPadOS beta 6, I get a crash just by simply selecting an item in the sidebar of a navigation view. The selected item is part of an app mode, with conforms to the Observation protocol:
import SwiftUI
import Observation
@main
struct MREAApp: App {
@State private var appModel = AppModel.shared
var body: some Scene {
WindowGroup {
ContentView()
.environment(appModel)
}
}
}
@Observable class AppModel {
static var shared = AppModel()
var selectedFolder: Folder? = nil
}
struct Folder: Hashable, Identifiable {
let id = UUID()
let name: String
}
struct ContentView: View {
@Environment(AppModel.self) private var appModel
var folders = [Folder(name: "Recents"), Folder(name: "Deleted"), Folder(name: "Custom")]
var body: some View {
NavigationSplitView {
SidebarView(appModel: appModel, folders: folders)
} detail: {
if let folder = appModel.selectedFolder {
Text(folder.name)
}
else {
Text("No selection")
}
}
}
}
struct SidebarView: View {
@Bindable var appModel: AppModel
var folders: [Folder]
var body: some View {
List(selection: $appModel.selectedFolder) {
ForEach(folders, id: \.self) { folder in
NavigationLink(value: folder) {
Text(folder.name)
}
}
}
}
}
To reproduce the bug, just tap on one of the item.
Oddly enough, this works fine in the Simulator.
macOS 14 beta 5 is not affected either.
Apple folks: FB12981860
Post not yet marked as solved
According to docs, .focusedObject() usage should be moved to .focusedValue() when migrating to @Observable, but there is no .focusedSceneValue() overload that accepts Observable like with .focusedValue(). So how are we supposed migrate .focusedSceneObject() to @Observable?
Post not yet marked as solved
******* TestData.swift ************************
struct Measures: Identifiable {
let id = UUID()
var dataSeq: Int
var value: Double
}
struct Items: Identifiable {
let id = UUID()
var name: String
var measures: [Measures]
}
struct chartItemInfo: Identifiable {
var id = UUID()
var testItem: String
var value: Double
}
var angleItem : [chartItemInfo]?
var degreeItem : [chartItemInfo]?
var grip1Item : [chartItemInfo]?
var grip2Item : [chartItemInfo]?
class TestData: ObservableObject {
@Published var angleItem : [chartItemInfo]?
@Published var degreeItem : [chartItemInfo]?
@Published var grip1Item : [chartItemInfo]?
@Published var grip2Item : [chartItemInfo]?
}
******** CalculatorViewModel.swift ******************************************
class CalculatorViewModel : NSObject, ObservableObject, Identifiable {
....
typealias test_Array = (time: String, swingNum: Int, dataSeqInSwing: Int, timeStampInSeq: Int, angle: Double, degree: Double, grip1: Double, grip2: Double)
....
@Published var testDBdata = [test_Array]()
@Published var chartDBdata = [chart_Array]() //
@StateObject var testData : TestData
var Testitems = [ (channel: "angle", data: testData.angleItem), (channel: "degree", data: testData.degreeItem), (channel: "grip1", data: testData.grip1Item), (channel: "grip2", data: testData.grip2Item)]. => Cannot use instance member 'testData' within property initializer; property initializers run before 'self' is available ?
purpose of this project: read FMDB data and then make Array with DB data.
and then i use these Array for displaying multi plot in Chart.
Post not yet marked as solved
iOS 17 introduced @Observable. that's an effective way to implement a stateful model object.
however, we will not be able to use @StateObject as the model object does not have ObservableObject protocol.
An advantage of using StateObject is able to make the object initializing once only for the view. it will keep going on until the view identifier is changed.
I put some examples.
We have a Observable implemented object.
@Observable final class Controller { ... }
then using like this
struct MyView: View {
let controller: Controller
init(value: Value) {
self.controller = .init(value: value)
}
init(controller: Controller) {
self.controller = controller
}
}
this case causes a problem that the view body uses the passed controller anyway.
even passed different controller, uses it.
and what if initializing a controller takes some costs, that decrease performance.
how do we manage this kind of use case?
anyway I made a utility view that provides an observable object lazily.
public struct ObjectProvider<Object, Content: View>: View {
@State private var object: Object?
private let _objectInitializer: () -> Object
private let _content: (Object) -> Content
public init(object: @autoclosure @escaping () -> Object, @ViewBuilder content: @escaping (Object) -> Content) {
self._objectInitializer = object
self._content = content
}
public var body: some View {
Group {
if let object = object {
_content(object)
}
}
.onAppear {
object = _objectInitializer()
}
}
}
ObjectProvider(object: Controller() { controller in
MyView(controller: controller)
}
for now it's working correctly.
Post not yet marked as solved
I have a class A and class B, and both of them are @Observable, and none of them are a view.
Class A has an instance of class B.
I want to be able to listen to changes in this instance of class B, from my class A.
Previously, by using ObservableObject, instead of the @Observable macro, every property that needed to be observable, had to be declared as a Publisher. With this new framework, everything seems to be automatically synthesised, and using a Publisher is no longer required, as all the properties are observable.
That being said, how can I have an equivalent using @Observable? Is this new macro only for view-facing classes?
Post not yet marked as solved
When I update a variable inside my model that is marked @Transient, my view does not update with this change. Is this normal? If I update a non-transient variable inside the model at the same time that I update the transient one, then both changes are propagated to my view.
Here is an example of the model:
@Model public class WaterData {
public var target: Double = 3000
@Transient public var samples: [HKQuantitySample] = []
}
Updating samples only does not propagate to my view.
Post not yet marked as solved
I have an issue with a View that owns @Observable object (Instantize it, and is owner during the existence) in the same notion as @StateObject, however when @State is used the viewModel is re-created and deallocated on every view redraw.
In the previous models, @StateObject were used when the View is owner of the object (Owner of the viewModel as example)
When @Observable object is used in the same notion, @State var viewModel = ViewModel() the viewModel instance is recreated on views redraws.
@StateObject was maintaining the same instance during the View existence, that however is not happening when used @Observable with @State.
Post not yet marked as solved
I created FB13074428 and a small sample project to demonstrate the bug.
https://github.com/jamiemcd/Apple-FB13074428
Basically, if a SwiftData class is marked as @Model and it has a computed property that depends on a relationship's stored property, the computed property does not trigger updates in SwiftUI when the underlying relationship changes its stored property. This is Xcode 15 Beta 8.
@Model
final class Airport {
var code: String
var name: String
var airplanes: [Airplane]
init(code: String, name: String, airPlanes: [Airplane]) {
self.code = code
self.name = name
self.airplanes = airPlanes
}
// Bug: This computed property is not triggering observation in AirportView when airplane.state changes. My understanding of the new observation framework is that it should.
var numberOfAirplanesDeparting: Int {
var numberOfAirplanesDeparting = 0
for airplane in airplanes {
if airplane.state == .departing {
numberOfAirplanesDeparting += 1
}
}
return numberOfAirplanesDeparting
}
}
AirportView should update because it has Text for airport.numberOfAirplanesDeparting
struct AirportView: View {
var airport: Airport
var body: some View {
List {
Section {
ForEach(airport.airplanes) { airplane in
NavigationLink(value: airplane) {
HStack {
Image(systemName: airplane.state.imageSystemName)
VStack(alignment: .leading) {
Text(airplane.name)
Text(airplane.type.name)
}
}
}
}
} header: {
Text(airport.name)
} footer: {
VStack(alignment: .leading) {
Text("Planes departing = \(airport.numberOfAirplanesDeparting)")
Text("Planes in flight = \(airport.numberOfAirplanesInFlight)")
Text("Planes landing = \(airport.numberOfAirplanesLanding)")
}
}
}
}
Post not yet marked as solved
At the moment, using Bindable for an object stored in Environment works in a cumbersome way:
struct ContentView: View {
@Environment(Model.self) var model
var body: some View {
@Bindable var model = model
VStack {
Text(model.someField.uppercased())
TextField("", text: $model.someField)
someSubView
}
.padding()
}
@ViewBuilder
var someSubView: some View {
@Bindable var model = model
TextField("", text: $model.someField)
}
}
A new @Bindable needs to be instantiated for each computed property in the view, which creates boilerplate I would like to avoid.
I made a new property wrapper which functions the same as the EnvironmentObject wrapper, but for Observable:
@propertyWrapper
struct EnvironmentObservable<Value: AnyObject & Observable>: DynamicProperty {
@Environment var wrappedValue: Value
public init(_ objectType: Value.Type) {
_wrappedValue = .init(objectType)
}
public init() {
_wrappedValue = .init(Value.self)
}
private var store: Bindable<Value>!
var projectedValue: Bindable<Value> {
store
}
mutating func update() {
store = Bindable(wrappedValue)
}
}
Example:
struct ContentView: View {
@EnvironmentObservable var model: Model
var body: some View {
VStack {
Text(model.someField.uppercased())
SubView(value: $model.someField)
someSubView
}
.padding()
}
var someSubView: some View {
TextField("", text: $model.someField)
}
}
I was wondering if there would be any downsides to using this method? In my testings it seems to behave the same, but I'm not sure if using this could have a performance impact.
Post not yet marked as solved
SwiftUI & SwiftData.
I have a view that lists SwiftData objects. Tapping on a list item navigates to a detail view. The list view also has a "New Object" button. Tapping it opens a sheet used to create a new object. There are, obviously, two possible outcomes from interacting with the sheet — a new object could be created or the user could cancel without creating a new object.
If the user creates a new object using the sheet, I want to open the detail view for that object. My thought was to do this in the onDismiss handler for the sheet. However, that handler takes no arguments.
What is best practice for handling this situation? In UIKit, I would return a Result<Object, Error> in a closure. That won't work here. What is the "correct" way to handle this that is compatible with SwiftData and the Observation framework?
davmans.
