UserDefaults

I already searched the internet for this, but I couldn't find a complete answer.

I have an app with favorites. I want to save these favorites after closing the app.

To save the changed data, one can work with Userdefaults.

I have the following code

List {
             Toggle(isOn: $userData.showFavoritesOnly) {
                    Text("show favorites").bold().underline()
                }

In another file

import Foundation

class SettingsViewModel: ObservableObject {
    
    @Published var isOn: Bool = UserDefaults.standard.bool(forKey: "isOn") {
        didSet {
            UserDefaults.standard.set(self.isOn, forKey: "isOn")
        }
    }
}

Any help is appreciated.