Multi window SwiftUI app using shared and not-shared model

ObservedObject

The @ObservedObject does not bind the ObservableObject to the view where it is defined. That means that when we change a value in one view, it is going to be propagated between the views as well.

Here is the code to make views with the shared state.

import SwiftUI
public class ContentViewModel: ObservableObject {
  @Published var value: String = ""
}
struct ContentView: View {
  
  @ObservedObject var viewModel: ContentViewModel = ContentViewModel()
  
  var body: some View {
    TextField("Value", text: $viewModel.value)
      .padding()
  }
  
  struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
      ContentView()
    }
  }
}

StateObject

The @StateObject is binded to a view. That means that each opened view gets its own state.

Here is the code to make views with its own independent values.

import SwiftUI
public class ContentViewModel: ObservableObject {
  @Published var value: String = ""
}
struct ContentView: View {
  
  @StateObject var viewModel: ContentViewModel = ContentViewModel()
  
  var body: some View {
    TextField("Value", text: $viewModel.value)
      .padding()
  }
  
  struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
      ContentView()
    }
  }
}

You can watch this 30 minutes video with the explanation of the difference between @ObservedObject and @StateObject