tricksy-timer.swift

import SwiftUI

struct ContentView: View {
    var body: some View {
        IceCreamView(viewModel: ViewModel(iceCream: "banana"))
    }
}

struct IceCreamView: View {
    @State var viewModel: ViewModel
    
    var body: some View {
        VStack {
            Text("Flavor: \(viewModel.iceCream)")
            
            // This random number changes every 1 second
            // and ideally it wouldn't
            Text("Enjoy your ice cream! \(arc4random_uniform(9999999))")
        }
        .overlay {
            // It changes due to this overlay
            Text("Ordered \(viewModel.secondsSinceCreation) second(s) ago")
                .padding(.top, 100)
        }
    }
}

@Observable class ViewModel {
    let iceCream: String
    var secondsSinceCreation = 0
    
    init(iceCream: String) {
        self.iceCream = iceCream
        
        Timer.scheduledTimer(withTimeInterval: 1.0, repeats: true) { timer in
            self.secondsSinceCreation += 1
            print("Called")
        }
    }
}