NSManaged Property causing DisclosureGroup animation problems in Swiftui - swiftui

Question

I have an NSManagedObject with NSManaged properties that control the expanded/collapsed state of disclosure groups. Here's an example:
/// Views that provides UI for app settings.
struct SettingsView: View {
#Binding var isExpanded: Bool
var body: some View {
let _ = Self._printChanges()
DisclosureGroup(isExpanded: $isExpanded, content: {
VStack {
Text("Hello world!")
Text("Hello world!")
Text("Hello world!")
Text("Hello world!")
Text("Hello world!")
}
}, label: {
HStack {
Text("Settings")
}
})
.padding([.leading,.trailing])
}
}
The view's parent calls it like this:
#EnvironmentObject var settings: SideBarSettings
.
.
.
SettingsView(isExpanded: $settings.isExpanded)
The disclosure group animation is lost when using NSManaged property. Animation is preserved when using any other non-NSManaged property even if the property is declared inside NSManagedObject.
Why is DisclosureGroup animation lost when using the NSManaged property?

Answer 1

After spending a few days on this, I'm accepting that the underlying problem is the way NSManaged properties work with SwiftUI. So, a possible solution would be to not use the NSManaged property at all in the DisclosureGroup and use a value type instead.
And use modifiers to init it and track changes on the new State var; like this:
struct SettingsView: View {
#Binding var isExpanded: Bool
#State private var isExpandedNonManaged = false // New property
var body: some View {
let _ = Self._printChanges()
DisclosureGroup(isExpanded: $isExpandedNonManaged, content: {
VStack {
Text("Hello world!")
Text("Hello world!")
Text("Hello world!")
Text("Hello world!")
Text("Hello world!")
}
}, label: {
HStack {
Text("Settings")
}
})
.onAppear {
isExpandedNonManaged = isExpanded // Initialize the State property
}
.onChange(of: isExpandedNonManaged) { newValue in
isExpanded = newValue // Update the managed property
}
}
}
Not elegant, nor scalable ... but it works.
Open to better solutions!
Update:
With a little help from this post, came up with a CustomDisclosureGroup that eliminates lots of code duplication.
public struct CustomDisclosureGroup<LabelContent: View, Content: View>: View {
var label: LabelContent
var content: Content
#Binding var isExpanded: Bool
public init(isExpanded: Binding<Bool>, #ViewBuilder label: () -> LabelContent, #ViewBuilder content: () -> Content) {
self.label = label()
self.content = content()
self._isExpanded = isExpanded
}
public init(labelString: String, isExpanded: Binding<Bool>, #ViewBuilder content: () -> Content) where LabelContent == Text {
self.init(isExpanded: isExpanded, label: { Text(labelString) }, content: content)
}
public var body: some View {
DisclosureGroup(isExpanded: $isExpanded) {
content
} label: {
label
}
}
}
#main
struct TestDisclosureApp: App {
#StateObject var topModel = TopModel()
var body: some Scene {
WindowGroup {
ContentView()
}
}
}
struct ContentView: View {
#EnvironmentObject var topModel: TopModel
#State var isExpanded1 = false
#State var isExpanded2 = false
var body: some View {
CustomDisclosureGroup(isExpanded: $isExpanded1, label: { Text("Label") }) {
HStack {
Text("Content1")
}
}
.padding()
CustomDisclosureGroup(labelString: "Label", isExpanded: $isExpanded2) {
HStack {
Text("Content2")
}
}
.padding()
}
}