I have a model like this:
protocol PurchasableProduct {
var randomId: String { get }
}
class Cart: Identifiable {
var items: [PurchasableProduct]
init(items: [PurchasableProduct]) {
self.items = items
}
}
class Product: Identifiable, PurchasableProduct {
var randomId = UUID().uuidString
var notes: String = ""
}
class DigitalGood: Identifiable, PurchasableProduct {
var randomId = UUID().uuidString
}
where items
conform to protocol PurchasableProduct
.
I want to build a View that shows cart like this:
struct CartView: View {
@State var cart: Cart
var body: some View {
List {
ForEach(cart.items.indices) { index in
CartItemView(item: self.$cart.items[index])
}
}
}
}
where CartItemView
is:
struct CartItemView: View {
@Binding var item: PurchasableProduct
var body: some View {
VStack {
if self.item is Product {
Text("Product")
} else {
Text("Digital Good")
}
}
}
}
That's working and give me result as This (screenshot)
But I want to extend this a but more that my items
element can be passed as a binding variable lets say as:
struct CartItemView: View {
@Binding var item: PurchasableProduct
var body: some View {
VStack {
if self.item is Product {
VStack {
TextField("add notes", text: (self.$item as! Product).notes) // ❌ Cannot convert value of type 'String' to expected argument type 'Binding<String>'
TextField("add notes", text: (self.$item as! Binding<Product>).notes) // ⚠️ Cast from 'Binding<PurchasableProduct>' to unrelated type 'Binding<Product>' always fails
}
} else {
Text("Digital Good")
}
}
}
}
What I'm trying to achieve is:
CartView
Not sure if thats syntax issue or my approach issue... how to cast this on body
to get the correct view based on type?
You may create a custom binding:
struct CartItemView: View {
@Binding var item: PurchasableProduct
var product: Binding<Product>? {
guard item is Product else { return nil }
return .init(
get: {
self.$item.wrappedValue as! Product
}, set: {
self.$item.wrappedValue = $0
}
)
}
var body: some View {
VStack {
if product != nil {
TextField("add notes", text: product!.notes)
} else {
Text("Digital Good")
}
}
}
}
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