Swift: Error converting type 'Binding<Subject>' when passing Observed object's property to child view - swift

Question

I want to load data from an API, then pass that data to several child views.
Here's a minimal example with one child view (DetailsView). I am getting this error:
Cannot convert value of type 'Binding<Subject>' to expected argument type 'BusinessDetails'
import Foundation
import SwiftUI
import Alamofire
struct BusinessView: View {
var shop: Business
class Observer : ObservableObject{
#Published public var shop = BusinessDetails()
#Published public var loading = false
init(){ shop = await getDetails(id: shop.id) }
func getDetails(id: String) async -> (BusinessDetails) {
let params = [
id: id
]
self.loading = true
self.shop = try await AF.request("https://api.com/details", parameters: params).serializingDecodable(BusinessDetails.self).value
self.loading = false
return self.shop
}
}
#StateObject var observed = Observer()
var body: some View {
if !observed.loading {
TabView {
DetailsView(shop: $observed.shop)
.tabItem {
Label("Details", systemImage: "")
}
}
}
}
}
This has worked before when the Observed object's property wasn't an object itself (like how the loading property doesn't cause an error).

Answer 1

When using async/await you should use the .task modifier and remove the object. The task will be started when the view appears, cancelled when it disappears and restarted when the id changes. This saves you a lot of effort trying to link async task lifecycle to object lifecycle. e.g.
struct BusinessView: View {
let shop: Business
#State var shopDetails = BusinessDetails()
#State var loading = false
var body: some View {
if loading {
Text("Loading")
}
else {
TabView {
DetailsView(shop: shopDetails)
.tabItem {
Label("Details", systemImage: "")
}
}
}
.task(id: shop.id) {
loading = true
shopDetails = await Self.getDetails(id: shop.id) // usually we have a try catch around this so we can show an error message
loading = false
}
}
// you can move this func somewhere else if you like
static func getDetails(id: String) async -> BusinessDetails{
let params = [
id: id
]
let result = try await AF.request("https://api.com/details", parameters: params).serializingDecodable(BusinessDetails.self).value
return result
}
}
}