import Foundation


class Food: ObservableObject {
    @Published var type: String = "vegetable"
    
    func changeType() {
        let tmp = ["vegetable", "fruit", "meat", "dairy"]
        let index = Int.random(in: 0..<tmp.count)
        self.type = tmp[index]
    }
}

import SwiftUI

struct ContentView: View {
    @ObservedObject var food: Food = Food()
    
    @EnvironmentObject var foodEn: Food
    
    init() {
        food.changeType()
    }
    
    var body: some View {
        VStack {
            Text("ObservedObject, \(food.type)")
                .padding()
            
            Text("EnvironmentObject,  \(foodEn.type)")
                .padding()
                .onAppear{
                    foodEn.changeType()
                }
            
            Spacer()
            Button(action: {
                food.changeType()
                foodEn.changeType()
            }, label: {
                Text("Change")
            })
            Spacer()
            
            CompareView()
        }
    }
}

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView()
    }
}

import SwiftUI

struct CompareView: View {
    @ObservedObject var food: Food = Food()
    
    @EnvironmentObject var foodEn: Food
    
    init() {
        food.changeType()
    }
    
    var body: some View {
        Text("CompareView-ObservedObject,  \(food.type)")
            .padding()
        
        Text("CompareView-EnvironmentObject,  \(foodEn.type)")
            .padding()
            .onAppear{
                foodEn.changeType()
            }
    }
}

struct CompareView_Previews: PreviewProvider {
    static var previews: some View {
        CompareView()
    }
}

import SwiftUI

@main
struct ccApp: App {
    let foodEn: Food = Food()
    
    var body: some Scene {
        WindowGroup {
            ContentView().environmentObject(foodEn)
        }
    }
}