SwiftUI ViewModel update - swiftui

Question

I have a View with many Buttons and if the User tap on a Button the Viewmodel need to update the current Button with the increased value.
class ProductVM: ObservableObject {
#Published var product : Product
init(product: Product) {
self.product = product
}
public func increaseAmount() {
var myInt = Int(self.product.amount) ?? 0
myInt += 1
self.product.amount = String(myInt)
print(myInt)
print("...")
}
}
the problem is the myInt is every time just 1 and the value can't be updated.
HOW can i update the value and save it in the current Model so that the View know its increased ??!!
struct singleButtonView: View {
#ObservedObject var productVM : ProductVM
func updatePos(){
self.productVM.increaseAmount()
}
}
and i call it with
singleButtonView(productVM: ProductVM(product: product))

Answer 1

Nested ObservableObjects need to be updated manually. Here is an example how this could look like:
class Product: ObservableObject, Identifiable, Codable {
let id: Int
let name: String
let prize: Double
#Published var amount: Int = 0
enum CodingKeys: String, CodingKey {
case id
case name
case prize
case amount
}
init() {
self.id = 0
self.name = "name"
self.prize = 0
}
init(id: Int, name: String, prize: Double) {
self.id = id
self.name = name
self.prize = prize
}
required init(from decoder: Decoder) throws {
let values = try decoder.container(keyedBy: CodingKeys.self)
id = try values.decode(Int.self, forKey: .id)
name = try values.decode(String.self, forKey: .name)
prize = try values.decode(Double.self, forKey: .prize)
amount = try values.decode(Int.self, forKey: .amount)
}
func encode(to encoder: Encoder) throws {
var container = encoder.container(keyedBy: CodingKeys.self)
try container.encode(id, forKey: .id)
try container.encode(name, forKey: .name)
try container.encode(prize, forKey: .prize)
try container.encode(amount, forKey: .amount)
}
}
class ProductVM: ObservableObject {
#Published var product: Product
var cancelable: AnyCancellable? = nil
init(product: Product) {
self.product = product
self.cancelable = product.objectWillChange.sink(receiveValue: {
self.objectWillChange.send()
})
}
public func increaseAmount() {
self.product.amount += 1
}
}
struct ContentView: View {
#ObservedObject var productVM = ProductVM(product: Product())
var body: some View {
VStack {
Button(action: {
self.productVM.increaseAmount()
}) {
Text("Add")
}
Text("\(self.productVM.product.amount)")
}
}
}
I hope this helps!
Credits