How do I make a currency calculations based on rounded times? - swiftui

Question

I have SwiftUI code which computes the time duration between two times (startTime and endTime) and rounds up to nearest 15 minutes. But how do I calculate the currency rate of $220 per hour from this duration?
I also seem to be struggling with organizing my code into view code (for SwiftUI) and also including the numerical code that runs in the background.
But here's my code I have so far with comments where I need to include this code.
import SwiftUI
struct ContentView: View {
#State private var startTime = Date().zeroSeconds
#State private var endTime = Date().zeroSeconds
#State private var number15Intervals = 0
#State private var amountDue = 0.0
var body: some View {
NavigationView {
Form {
Section(header: Text("Enter Case Times:")) {
DatePicker("Start Time", selection: $startTime , displayedComponents: .hourAndMinute)
DatePicker("End Time", selection: $endTime, in: startTime..., displayedComponents: .hourAndMinute)
}
Section(header: Text("Case Duration:")) {
Text("duration = \(self.duration) min")
Text("duration (15m) = \(self.duration15) min")
}
Section(header: Text("Amount Due:")) {
// What code do I put here to calculate currency (US dollars)
// which equals time (rounded up by 15 min) times a rate of $220 per hour?
Text(amountDue, format: .currency(code: Locale.current.currencyCode ?? "USD"))
}
}
.navigationTitle("DDA Rates Calculator")
}
}
var duration: TimeInterval {
guard endTime > startTime else {
return 0
}
let dateIntervalMinutes = DateInterval(start: startTime, end: endTime).duration / 60
return dateIntervalMinutes
}
var duration15: TimeInterval {
return (self.duration/15.0).rounded(.up)*15
}
}
extension Date {
var zeroSeconds: Date {
let calendar = Calendar.current
let dateComponents = calendar.dateComponents([.hour, .minute], from: self)
return calendar.date(from: dateComponents) ?? self
}
}
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView()
}
}
Sorry if I'm not too clear here. I've tried all sorts of ways to do this but always seem to get all sorts of errors from XCode. I think it would be more confusing to show what I've tried so far since I tried it so many ways without success. I'm not understanding the scope and how to reference variables properly in SwiftUI.

Answer 1

You can replace your amountDue #State variable with a computed property:
var amountDue: Double {
duration15 / 60 * 220
}
(You can also remove the unused number15Intervals)