Why My second view cannot jump back to the root view properly - swift

Question

My App currently has two pages, first page has a circle plus button which could lead us to a second page. Basically, I have a save button which after clicking it, we could get back to the rood page. I followed this link for going back to root view. I tried the most up voted code, his code works perfectly. I reduced his code to two scene (basically the same scenario as mine), which also works perfectly. But then I don't know why my own code, pasted below, doesn't work. Basically my way of handling going back to root view is the same as the one in the link.
//
// ContentView.swift
// refridgerator_app
//
// Created by Mingtao Sun on 12/22/20.
//
import SwiftUI
import UIKit
#if canImport(UIKit)
extension View {
func hideKeyboard() {
UIApplication.shared.sendAction(#selector(UIResponder.resignFirstResponder), to: nil, from: nil, for: nil)
}
}
#endif
struct ContentView: View {
#EnvironmentObject private var fridge : Fridge
private var dbStartWith=0;
#State var pushed: Bool = false
#State private var selection = 1;
#State private var addFood = false;
var body: some View {
TabView(selection: $selection) {
NavigationView {
List(fridge.container!){
food in NavigationLink(destination: FoodView()) {
Text("HI")
}
}.navigationBarTitle(Text("Fridge Items"), displayMode: .inline)
.navigationBarItems(trailing:
NavigationLink(destination: AddFoodView(pushed: self.$pushed),isActive: self.$pushed) {
Image(systemName: "plus.circle").resizable().frame(width: 22, height: 22)
}.isDetailLink(false) )
}
.tabItem {
Image(systemName: "house.fill")
Text("Home")
}
.tag(1)
Text("random tab")
.font(.system(size: 30, weight: .bold, design: .rounded))
.tabItem {
Image(systemName: "bookmark.circle.fill")
Text("profile")
}
.tag(0)
}.environmentObject(fridge)
}
}
struct FoodView: View{
var body: some View{
NavigationView{
Text("food destination view ");
}
}
}
struct AddFoodView: View{
#Binding var pushed : Bool
#EnvironmentObject private var fridgeView : Fridge
#State private var name = ""
#State private var count : Int = 1
#State private var category : String = "肉类";
#State var showCategory = false
#State var showCount = false
var someNumberProxy: Binding<String> {
Binding<String>(
get: { String(format: "%d", Int(self.count)) },
set: {
if let value = NumberFormatter().number(from: $0) {
self.count = value.intValue;
}
}
)
}
var body: some View{
ZStack{
NavigationView{
VStack{
Button (action: {
self.pushed = false ;
//let tempFood=Food(id: fridgeView.index!,name: name, count: count, category: category);
//fridgeView.addFood(food: tempFood);
} ){
Text("save").foregroundColor(Color.blue).font(.system(size: 18,design: .default)) }
}.navigationBarTitle("Three")
}
ZStack{
if self.showCount{
Rectangle().fill(Color.gray)
.opacity(0.5)
VStack(){
Spacer(minLength: 0);
HStack{
Spacer()
Button(action: {
self.showCount=false;
}, label: {
Text("Done")
}).frame(alignment: .trailing).offset(x:-15,y:15)
}
Picker(selection: $count,label: EmptyView()) {
ForEach(1..<100){ number in
Text("\(number)").tag("\(number)")
}
}.labelsHidden()
} .frame(minWidth: 300, idealWidth: 300, maxWidth: 300, minHeight: 250, idealHeight: 100, maxHeight: 250, alignment: .top).fixedSize(horizontal: true, vertical: true)
.background(RoundedRectangle(cornerRadius: 27).fill(Color.white.opacity(1)))
.overlay(RoundedRectangle(cornerRadius: 27).stroke(Color.black, lineWidth: 1))
.offset(x:10,y:-10)
Spacer()
}
if self.showCategory{
let categoryArr = ["肉类","蔬菜类","饮料类","调味品类"]
ZStack{
Rectangle().fill(Color.gray)
.opacity(0.5)
VStack(){
Spacer(minLength: 0);
HStack{
Spacer()
Button(action: {
self.showCategory=false;
}, label: {
Text("Done")
}).frame(alignment: .trailing).offset(x:-15,y:15)
}
Picker(selection: $category,label: EmptyView()) {
ForEach(0..<categoryArr.count){ number in
Text(categoryArr[number]).tag(categoryArr[number])
}
}.labelsHidden()
} .frame(minWidth: 300, idealWidth: 300, maxWidth: 300, minHeight: 250, idealHeight: 100, maxHeight: 250, alignment: .top).fixedSize(horizontal: true, vertical: true)
.background(RoundedRectangle(cornerRadius: 27).fill(Color.white.opacity(1)))
.overlay(RoundedRectangle(cornerRadius: 27).stroke(Color.black, lineWidth: 1))
Spacer()
}.offset(x:10,y:20)
}
}
}.animation(.easeInOut)
}
}
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView()
}
}
If you read my code carefully, there are some variables are missing referencing. That's because I pasted part of the code that relates to my issue.
Food Class
//
// Food.swift
// refridgerator_app
//
// Created by Mingtao Sun on 12/23/20.
//
import Foundation
class Food: Identifiable {
init(id:Int, name: String, count: Int, category: String){
self.id=id;
self.name=name;
self.count=count;
self.category=category;
}
var id: Int
var name: String
var count: Int
var category: String
}
Fridge class
//
// Fridge.swift
// refridgerator_app
//
// Created by Mingtao Sun on 12/27/20.
//
import Foundation
class Fridge: ObservableObject{
init(){
db=DBhelper();
let result = setIndex(database: db!);
self.index = result.1;
self.container=result.0;
}
var db:DBhelper?
var index : Int?
#Published var container : [Food]?;
func setIndex(database: DBhelper) -> ([Food],Int){
let foodList : [Food] = database.read();
var index=0;
for food in foodList{
index = max(food.id,index);
}
return (foodList,(index+1));
}
func updateindex(index: inout Int){
index=index+1;
}
func testExist(){
if let data = db {
print("hi")
}
else{
print("doesnt exist")
}
}
func addFood(food:Food){
self.db!.insert(id: self.index!, name: food.name, count:food.count, category: food.category);
self.container!.append(food);
}
}

Answer 1

Because you implemented a new NaviagtionView in AddFoodView. Simply remove this and it should work. Look at the link you provided. There is no NavigationView in the child.
Correct me if Im wrong but the core code parts here that produce this issue are as follows:
Here you start:
struct ContentView: View {
#State var pushed: Bool = false
// Deleted other vars
var body: some View {
TabView(selection: $selection) {
NavigationView {
List(fridge.container!){
food in NavigationLink(destination: FoodView()) {
Text("HI")
}
}.navigationBarTitle(Text("Fridge Items"), displayMode: .inline)
.navigationBarItems(trailing:
// Here you navigate to the child view
NavigationLink(destination: AddFoodView(pushed: self.$pushed),isActive: self.$pushed) {
Image(systemName: "plus.circle").resizable().frame(width: 22, height: 22)
}.isDetailLink(false) )
}
Here you land and want to go back to root:
struct AddFoodView: View{
#Binding var pushed : Bool
// Deleted the other vars for better view
var body: some View{
ZStack{
NavigationView{ // <-- remove this
VStack{
Button (action: {
// here you'd like to go back
self.pushed = false;
} ){
Text("save").foregroundColor(Color.blue).font(.system(size: 18,design: .default)) }
}.navigationBarTitle("Three")
}
For the future:
I have the feeling you might have troubles with the navigation in general.
Actually it is really simple:
You implement one NavigationView at the "root" / start of your navigation.
From there on you only use NavigationLinks to go further down to child pages. No NavigationView needed anymore.