Simple example of MMVM with SwiftUI.

MVVMSwiftUI.swift

import Foundation
import SwiftUI
import Combine

let dateFormatter: DateFormatter = {
    let dateFormatter = DateFormatter()
    dateFormatter.locale = Locale(identifier: "en_US_POSIX")
    dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ssZ"
    return dateFormatter
}()

class MainController: ObservableObject {
    static let shared = MainController()
    @Published var contentViewModel: ContentView.Model = .init()
}

struct ContentView: View {
    class Model: ObservableObject {
        @Published var dateString: String = dateFormatter.string(from: Date())
    }
    
    @ObservedObject var model: Model
    
    var body: some View {
        VStack {
            Text(model.dateString)
            Button(action: {
                self.model.dateString = dateFormatter.string(from: Date())
            }, label: { Text("Set Date") })
        }
    }
}