How to conform AppDelegate to ObservableObject?

Question

I'm trying to observe a value in macOS AppDelegate but I got an Error:

ContentView.swift:14:6: Generic struct 'ObservedObject' requires that 'NSApplicationDelegate?' conform to 'ObservableObject'

When I try to cast the object into ObservedObject with as! ObservedObject I have another Error:

ContentView.swift:14:6: Generic struct 'ObservedObject' requires that 'ObservedObject' conform to 'ObservableObject'

AppDelegate.swift:

import Cocoa
import SwiftUI
import Combine

@NSApplicationMain
class AppDelegate: NSObject, ObservableObject, NSApplicationDelegate  {
    var isFocused = true
    
    // Other code app life-cycle functions
}

ContentView.swift:

import SwiftUI
import Combine

struct ContentView: View {
    @ObservedObject var appDelegate = NSApplication.shared.delegate
    
    // Other UI code
}

Answer 1

This looks like mix of concepts.. I'd recommend to avoid such... instead created explicit observable class.

Like below (sketch)

class AppState: ObservableObject {
  @Published var isFocused = true
}

@NSApplicationMain
class AppDelegate: NSObject, NSApplicationDelegate  {
    var appState = AppState()
    
    // Other code app life-cycle functions

     // in place where ContentView is created
     ...
     ContentView().environmentObject(self.appState)
     ...
}

and in ContentView just use it

struct ContentView: View {
    @EnvironmentObject var appState: AppState
    
    // Other UI code

    var body: some View {
       // .. use self.appState.isFocused where needed
    }
}