Example view model class used during my Advanced SwiftUI workshop

ListViewModel.swift

import SwiftUI

struct Item: Equatable, Identifiable {
    let id = UUID()
    var title: String
    var isFavorite = false
}

@MainActor class ListViewModel: ObservableObject {
    @Published private(set) var items: [Item] = []
    private var isLoadingMoreItems = false

    init() {
        addItems()
    }

    func loadMoreItems() {
        guard !isLoadingMoreItems else { return }
        isLoadingMoreItems = true

        Task {
            try! await Task.sleep(nanoseconds: 1_000_000_000)
            addItems()
            isLoadingMoreItems = false
        }
    }

    func toggleFavorite(forItem item: Item) async throws {
        try await Task.sleep(nanoseconds: 1_000_000_000)

        guard let index = items.firstIndex(where: { $0.id == item.id }) else {
            return
        }

        items[index].isFavorite.toggle()
    }

    private func addItems() {
        items += (items.count..<items.count + 50).map { index in
            Item(title: "Item \(index)")
        }
    }
}