On TextField select, all tab views re-render

ContentView.swift

import SwiftUI
import CoreData

struct ContentView: View {
    @Environment(\.managedObjectContext) private var viewContext
    
    @ObservedObject var viewModel1: ViewModel = ViewModel()
    @ObservedObject var viewModel2: ViewModel = ViewModel()
    @ObservedObject var viewModel3: ViewModel = ViewModel()
    @ObservedObject var viewModel4: ViewModel = ViewModel()
    
    var body: some View {
        TabView {
            SimpleView(viewModel: self.viewModel1, people: viewModel1.people, num: 1)
            .tabItem {
                Text("1")
            }.onAppear{
                print("tab 1 appear")
                viewModel1.getPeople(num: 1)
            }
            SimpleView(viewModel: self.viewModel2, people: viewModel2.people, num: 2)
            .tabItem {
                Text("2")
            }.onAppear{
                print("tab 2 appear")
                viewModel2.getPeople(num: 2)
            }
            SimpleView(viewModel: self.viewModel3, people: viewModel3.people, num: 3)
            .tabItem {
                Text("3")
            }.onAppear{
                print("tab 3 appear")
                viewModel3.getPeople(num: 3)
            }
            SimpleView(viewModel: self.viewModel4, people: viewModel4.people, num: 4)
            .tabItem {
                Text("4")
            }.onAppear{
                print("tab 4 appear")
                viewModel4.getPeople(num: 4)
            }
        }
    }
}

SimpleView.swift

import SwiftUI

struct SimpleView: View {
    
    @State var text: String = ""
    @State var viewModel: ViewModel
    var people: [Person]
    var num: Int
    
    var body: some View {
        VStack {
            TextField("Enter text", text: self.$text)
            
            ForEach(viewModel.people) { person in
                Text(person.name)
            }
        }.onAppear {
            print("\(num) simple view appear")
            viewModel.getPeople(num: num)
        }
    }
}

TabSelectionContentView.swift

// ALTERNATIVE CONTENT VIEW TAB SELECTION OPTION

/* 1 simple view appear
1 get people
4 simple view appear
4 get people
tapped tab 4
2 simple view appear
2 get people
3 simple view appear
3 get people
*/

import SwiftUI
import CoreData

struct ContentView: View {
    @Environment(\.managedObjectContext) private var viewContext
    
    @State private var selectedTab = 1
    
    @ObservedObject var viewModel1: ViewModel = ViewModel()
    @ObservedObject var viewModel2: ViewModel = ViewModel()
    @ObservedObject var viewModel3: ViewModel = ViewModel()
    @ObservedObject var viewModel4: ViewModel = ViewModel()
    
    
    var body: some View {
        TabView(selection: $selectedTab) {
            SimpleView(viewModel: viewModel1, people: viewModel1.people, num: 1)
                .onTapGesture {
                    self.selectedTab = 1
                    print("tapped tab 1")
                }
                .tabItem {
                    Image(systemName: "star")
                    Text("1")
                }
                .tag(1)
            SimpleView(viewModel: viewModel2, people: viewModel2.people, num: 2)
                .onTapGesture {
                    self.selectedTab = 2
                    print("tapped tab 2")
                }
                .tabItem {
                    Image(systemName: "star")
                    Text("2")
                }
                .tag(2)
            SimpleView(viewModel: viewModel3, people: viewModel3.people, num: 3)
                .onTapGesture {
                    self.selectedTab = 3
                    print("tapped tab 3")
                }
                .tabItem {
                    Image(systemName: "star")
                    Text("3")
                }
                .tag(3)
            SimpleView(viewModel: viewModel4, people: viewModel4.people, num: 4)
                .onTapGesture {
                    self.selectedTab = 4
                    print("tapped tab 4")
                }
                .tabItem {
                    Image(systemName: "star")
                    Text("4")
                }
                .tag(4)
        }.ignoresSafeArea(.keyboard, edges: .bottom)
    }
}

ViewModel.swift

import Foundation


struct Person: Identifiable, Equatable {
    let id = UUID()
    let name: String
}

class ViewModel: ObservableObject {
    @Published var people: [Person] = []
    
    func getPeople(num: Int) {
        print("\(num) get people")
        DispatchQueue.main.async {
            let person = Person(name: "Hank \(num)")
            self.people.append(person)
        }
    }
    
}

Flow

1. Run App
2. Click Tab 4
3. Focus textfield

Result:

// ON LOAD
1 simple view appear
1 get people
tab 1 appear
1 get people

// SELECT TAB 4
4 simple view appear
4 get people
tab 4 appear
4 get people

// FOCUS TAB 4 TEXT FIELD -> ALL TABS RENDER
2 simple view appear
2 get people
tab 2 appear
2 get people
3 simple view appear
3 get people
tab 3 appear
3 get people
tab 1 appear
1 get people
1 simple view appear
1 get people

Added TabSelectionContentView.swift to show tab number condition implementation, similarly the views and vm render on text field focus