Views observing a Core Data object are not updating - swiftui

Question

I have a Core Data object called Config on ContentView.
This object is created like this:
#ObservedObject private var config = Config.with(PersistenceController.shared.context)!
config has 3 boolean properties: turnedOn, isSoft, and willAppear.
turnedON and willAppear are created in a way that if turnedON is true, willAppear must be false and vice-versa.
Now I pass config to 3 toggle switches and let the user adjust each one, true or false, but remember, if the user turns turnedON true, willAppear must be false and vice-versa. The same is true if the user turns willAppear true, in that canse turnedON must switch to false and vice-versa too.
So I pass config to the toggle switches like this on ContentView:
CustomToggle("Turn it on?"),
config,
coreDataBooleanPropertyName:"turnedOn")
CustomToggle("Is it soft?"),
config,
coreDataBooleanPropertyName:"isSoft")
CustomToggle("Will it appear?"),
config,
coreDataBooleanPropertyName:"willAppear")
and this is CustomToggle...
import SwiftUI
import CoreData
struct CustomToggle: View {
#State private var status:Bool
private let title: String
private let coreDataBooleanPropertyName:String
#ObservedObject private var config:Config {
didSet {
switch coreDataBooleanPropertyName {
case "isSoft":
self.status = config.isSoft
case "turnedOn":
self.status = config.turnedOn
case "willAppear":
self.status = config.willAppear
default:
break
}
}
}
init(_ title:String,
_ config:Config,
coreDataBooleanPropertyName:String) {
self.title = title
self.config = config
self.coreDataBooleanPropertyName = coreDataBooleanPropertyName
self.status = defaultStatus
switch coreDataBooleanPropertyName {
case "isSoft":
self.status = config.isSoft
case "turnedOn":
self.status = config.turnedOn
case "willAppear":
self.status = config.willAppear
default:
break
}
}
var body: some View {
Toggle(isOn: $status, label: {
ControlTitle(title)
})
.toggleStyle(CheckboxStyle())
.onChange(of: status, perform: { newStatus in
switch coreDataBooleanPropertyName {
case "isSoft":
config.isSoft = newStatus
case "turnedOn":
config.turnedOn = newStatus
config.willAppear = !newStatus
case "willAppear":
config.willAppear = newStatus
config.turnedOn = !newStatus
default:
return
}
let coreDataContext = PersistenceController.shared.context
do {
try coreDataContext.save()
}
catch let error{
print(error.localizedDescription)
}
})
struct CheckboxStyle: ToggleStyle {
func makeBody(configuration: Self.Configuration) -> some View {
return HStack {
Image(systemName: configuration.isOn ? "checkmark.circle.fill" : "circle")
.resizable()
.frame(width: 24, height: 24)
.foregroundColor(configuration.isOn ? Color.from("ffba00") : .gray)
.font(.system(size: 20, weight: .bold, design: .default))
.onTapGesture {
configuration.isOn.toggle()
}
configuration.label
Spacer()
}
}
}
I have tested the core data entry config and it works properly but the toggle switches willAppear and turnedOn do not update when one or the other are selected.
What am I missing?

Answer 1

Instead of didSet, which will not fire if just a property of your object changes, you could observe its changes via objectWillChange (note inline comments as well):
Toggle(isOn: $status, label: {
ControlTitle(title)
})
.onReceive(config.objectWillChange) { _ in
//run the code from your didSet here
//note that you *may* need to use something like DispatchQueue.main.async { } in here to get the updated values of the object since the values may not be updated until the next run loop -- I'm unsure of how this will behave with CoreData objects
}
.onChange(of: status, perform: { newStatus in
//etc