How to access a global environment object in a class?

Question

I have a class that needs to update a global environment object. I can pass that environment object between my structs all day, but how do I allow a class object to access the same variable?

import SwiftUI

class Global: ObservableObject
{
    @Published var num = 10
}

class MyClass:ObservableObject
{
    @Published var mode = 1
    @EnvironmentObject var global: Global

    func updateMode()
    {
        self.mode += 1
        global.num += 1
    }
}

@main
struct MyApp: App
{
    let settings = Global()
    var body: some Scene {
        WindowGroup {
            ContentView()
                .environmentObject(settings)
            }
    }
}

struct ContentView: View
{
    @EnvironmentObject var global: Global
    @ObservedObject var myClass = MyClass()
    
    var body: some View
    {
        VStack
        {
            Text("Setting \(global.num)")
            Text("Mode \(myClass.mode)")

            Button("Click Me", action: {myClass.updateMode()})
        }
        .padding()
    }
}

The following code gives an error:

Fatal Error: No ObservableObject of type Global found. A View.environmentObject(_:) for Global maybe missing an ancestor of this view.

I could pass the global object into myClass.updateMode, but then it doesn't seem very global at that point? I would have thought there must be a better way.

Answer 1

A possible approach is to make it shared (and don't use @EnvironmentObject anywhere outside SwiftUI view - it is not designed for that):

class Global: ObservableObject
{
    static let shared = Global()

    @Published var num = 10
}

class MyClass:ObservableObject
{
    @Published var mode = 1
    let global = Global.shared    // << here !!

// ...
}

@main
struct MyApp: App
{
    @StateObject var settings = Global.shared  // << same !!
// ...
}