Every time I insert a subclass (MYShapeLayer) into the model context, the app crashes with an error:
DesignerPlayground crashed due to fatalError in BackingData.swift at line 908. Never access a full future backing data - PersistentIdentifier(id: SwiftData.PersistentIdentifier.ID(backing: SwiftData.PersistentIdentifier.PersistentIdentifierBacking.managedObjectID(0xb2dbc55f3f4c57f2 <x-coredata://B1E3206B-40DE-4185-BC65-4540B4705B40/MYShapeLayer/p1>))) with Optional(A6CA4F89-107F-4A66-BC49-DD7DAC689F77)
struct ContentView: View {
@Environment(\.modelContext) private var modelContext
@Query private var designs: [MYDesign]
var layers: [MYLayer] {
designs.first?.layers ?? []
}
var body: some View {
NavigationStack {
List {
ForEach(layers) { layer in
Text(layer.description)
}
}
.onAppear {
let design = MYDesign(title: "My Design")
modelContext.insert(design)
try? modelContext.save()
}
.toolbar {
Menu("Add", systemImage: "plus") {
Button(action: addTextLayer) {
Text("Add Text Layer")
}
Button(action: addShapeLayer) {
Text("Add Shape Layer")
}
}
}
}
}
private func addTextLayer() {
if let design = designs.first {
let newLayer = MYLayer(order: layers.count, kind: .text)
newLayer.design = design
modelContext.insert(newLayer)
try? modelContext.save()
}
}
private func addShapeLayer() {
if let design = designs.first {
let newLayer = MYShapeLayer(shapeName: "Ellipse", order: layers.count)
newLayer.design = design
modelContext.insert(newLayer)
try? modelContext.save()
}
}
}
#Preview {
ContentView()
.modelContainer(for: [MYDesign.self, MYLayer.self, MYShapeLayer.self], inMemory: true)
}
@Model
final class MYDesign {
var title: String = ""
@Relationship(deleteRule: .cascade, inverse: \MYLayer.design)
var layers: [MYLayer] = []
init(title: String = "") {
self.title = title
}
}
@available(iOS 26.0, macOS 26.0, *)
@Model
class MYLayer {
var design: MYDesign!
var order: Int = 0
var title: String = ""
init(order: Int = 0, title: String = "New Layer") {
self.order = order
self.title = title
}
}
@available(iOS 26.0, macOS 26.0, *)
@Model
class MYShapeLayer: MYLayer {
var shapeName: String = ""
init(shapeName: String, order: Int = 0) {
self.shapeName = shapeName
super.init(order: order)
}
}
