Core Data computed property always returns 0

Question

I am learning SwiftUI and creating a very simple app where some Ints are inputted on one screen (Itemsheet), a calculation is run in app.xcdatamodel and they are outputted on ContentView.

However, the computed value is driving me crazy. It always seems to show as 0. I'd love to hear if anyone has any ideas why?

Here is my code:

ItemSheet.swift

@Environment(\.managedObjectContext) private var viewContext

Stepper("\(days) days", value: $days)
Stepper("\(cost)€", value: $cost)

app.xcdatamodel

extension Pricing {

    @nonobjc public class func fetchRequest() -> NSFetchRequest<Pricing> {
        return NSFetchRequest<Pricing>(entityName: "Pricing")
    }

@NSManaged public var days: Int16
@NSManaged public var cost: Int16
public var costPerDay: String {
        get {
            if (self.cost > 0) {
                let newValue = String(format: "%.0f", "Cost per day: \(cost) / \(days)")
                return newValue
            }
            else {
                return "add cost"
            }
        }
        set {
            self.costPerDay = newValue
        }
    }
}

ContentView.swift

struct ContentView: View {
    @Environment(\.managedObjectContext) private var viewContext

    @FetchRequest(entity: Clothing.entity(), sortDescriptors: [])
    var clothing: FetchedResults<Clothing>

var body: some View {
ForEach(clothing) { item in
Text("Days: \(item.days)")
Text("Cost: \(item.cost)")
Text("Cost per Days: \(item.costPerDay)")

}
}
}

Both the other Text views (Text("Days: \(item.days)")and Text("Cost: \(item.cost)")) are working fine, so guessing I am making a rookie error in the core data model somewhere?

Thank you!

Answer 1

Change your string to

String(format: "Cost per day: %.0f",  Double(cost / days))

"%.0f" is for Float or Double you are dealing with Int16