Updating EnvironmentObject in child view causes view to pop - ios

Question

I have a child view that updates an EnvironmentObject that then causes the child view to pop back to its parent view. I am creating an app that uses similar "Like" functionality from this tutorial: https://www.hackingwithswift.com/books/ios-swiftui/letting-the-user-mark-favorites
Every time the like button is clicked and the EnvironmentObject likes object is updated, the view pops to the previous (ProductGridView) view instead of staying on the child view (ProductDetailView).
struct ContentView: View {
#State private var tabSelection = 0
#ObservedObject var products = Products()
#ObservedObject var favorites = Favorites()
var body: some View {
VStack {
TabView(selection: $tabSelection) {
NavigationView{
ProductGridView()
}
.tabItem { Image(systemName: "megaphone")
Text("Products")
}.tag(0)
.environmentObject(products)
.environmentObject(favorites)
}
struct ProductGridView: View {
var columns: [GridItem] = Array(repeating: .init(.flexible()), count: 2)
#EnvironmentObject var products: Products
#EnvironmentObject var favorites: Favorites
var body: some View {
VStack{
ScrollView(.vertical, showsIndicators: false) {
LazyVGrid(columns: columns, alignment: .leading, spacing: 20) {
ForEach(products.products, content: {
product in
NavigationLink(destination: ProductDetailView(product: product)) {
ProductCellView(product: product)
.padding(.horizontal, 10)
}
})
}
}.onAppear() {
self.products.fetchData()
}
}
struct ProductDetailView: View {
let product: Product
#EnvironmentObject var favorites: Favorites
var body: some View {
ScrollView(showsIndicators: false) {
VStack{
ProductImageView(product: product)
Button(action: {
if favorites.contains(product) {
favorites.remove(product) //Updating here causes issue
} else {
favorites.add(product) //Updating here causes issue
}
}) {
if favorites.contains(product){
Image(systemName: "heart.fill")
}
else{
Image(systemName: "heart")
}
}
}
class Favorite : Identifiable, Encodable {
var id = UUID()
var name: String
...
class Favorites: ObservableObject {
#Published private var products: [String]?
...
struct Product: Identifiable{
let id = UUID()
let productname: String
...

Answer 1

It looks like your fetch data call may be causing the issue.
struct YourContentView: View {
#State private var tabSelection = 0
#ObservedObject var products = Products()
#ObservedObject var favorites = Favorites()
var body: some View {
VStack {
TabView(selection: $tabSelection) {
NavigationView{
ProductGridView()
}
.tabItem { Image(systemName: "megaphone")
Text("Products")
}.tag(0)
.environmentObject(products)
.environmentObject(favorites)
}
}
}
}
struct ProductDetailView: View {
let product: Product
#EnvironmentObject var favorites: Favorites
var body: some View {
ScrollView(showsIndicators: false) {
VStack{
Image(systemName: "photo")
.resizable()
.scaledToFit()
Button {
if favorites.products?.contains(product) ?? false {
favorites.remove(product) //Updating here causes issue
} else {
favorites.add(product) //Updating here causes issue
}
} label: {
if favorites.products?.contains(product) ?? false{
Image(systemName: "heart.fill")
}
else{
Image(systemName: "heart")
}
}
}
}
}
}
struct ProductCellView: View {
#State var product: Product
var body: some View {
HStack {
Image(systemName: "photo")
Text(product.productname)
}
}
}
struct ProductGridView: View {
let columns: [GridItem] = Array(repeating: .init(.flexible()), count: 2)
#EnvironmentObject var products: Products
#EnvironmentObject var favorites: Favorites
var body: some View {
VStack{
ScrollView(.vertical, showsIndicators: false) {
LazyVGrid(columns: columns, alignment: .leading, spacing: 20) {
ForEach(products.products, content: {
product in
NavigationLink(destination: ProductDetailView(product: product)) {
ProductCellView(product: product)
.padding(.horizontal, 10)
}
})
}
}.onAppear() {
self.products.fetchData()
}
}
}
}
class Favorites: ObservableObject {
#Published var products: [Product]? = []
init() {}
func remove(_ product: Product) {
products?.removeAll(where: { $0.id == product.id })
}
func add(_ product: Product) {
products?.append(product)
}
}
class Products: ObservableObject, Identifiable {
#Published var products: [Product]
init() {
products = [.init(productname: "ApplePie"), .init( productname: "Cheeseburger")]
}
func fetchData() {
// uncommenting this code will cause product grid view to reload because it relies on products
// products = [.init(productname: "ApplePie"), .init( productname: "Cheeseburger")]
}
}
struct Product: Identifiable, Equatable {
let id = UUID()
let productname: String
public static func ==(lhs: Product, rhs: Product) -> Bool {
lhs.id == rhs.id
}
}