How to get appropriate decimal/double currency value with decimal point? - swift

Question

How do I get to the proper value of the the amount entered in textfield? Assuming my dollar value is 50.05, I noticed that when I try to access:
bindingManager.text.decimal
I get 5005. What am I doing wrong to not get 50.05?
import SwiftUI
struct ContentView_Previews: PreviewProvider {
static var previews: some View {
ContentView()
}
}
struct ContentView: View {
#ObservedObject private var bindingManager = TextBindingManager(amount: 0)
var decimal: Decimal { bindingManager.text.decimal / pow(10, Formatter.currency.maximumFractionDigits) }
var maximum: Decimal = 999_999_999.99
#State private var lastValue: String = ""
#State private var locale: Locale = .current {
didSet { Formatter.currency.locale = locale }
}
var body: some View {
VStack(alignment: .leading) {
TextField(bindingManager.text, text: $bindingManager.text)
.keyboardType(.numberPad)
.multilineTextAlignment(.trailing) // this will keep the text aligned to the right
.onChange(of: bindingManager.text) { string in
if string.decimal > maximum {
self.bindingManager.text = lastValue
} else {
self.bindingManager.text = decimal.currency
lastValue = self.bindingManager.text
}
return
}
}
.padding()
.onAppear {
Formatter.currency.locale = locale
}
}
}
class TextBindingManager: ObservableObject {
#Published var text: String = ""
var amount: Decimal = .zero
init(amount: Decimal) {
self.amount = amount
self.text = Formatter.currency.string(for: amount) ?? "$0.00"
}
}
fileprivate extension Formatter {
static let currency: NumberFormatter = .init(numberStyle: .currency)
}
extension NumberFormatter {
convenience init(numberStyle: Style) {
self.init()
self.numberStyle = numberStyle
}
}
extension StringProtocol where Self: RangeReplaceableCollection {
var digits: Self { filter (\.isWholeNumber) }
}
extension String {
var decimal: Decimal { Decimal(string: digits) ?? 0 }
}
extension Decimal {
var currency: String { Formatter.currency.string(for: self) ?? "" }
}

Answer 1

You just need to divide the decimal value by the number of maximum fraction digits. Same as it is being done with the decimal instance property of your ContentView:
var decimal: Decimal { bindingManager.text.decimal / pow(10, Formatter.currency.maximumFractionDigits) }
.onChange(of: bindingManager.text) { string in
if string.decimal > maximum {
self.bindingManager.text = lastValue
} else {
self.bindingManager.text = decimal.currency
lastValue = self.bindingManager.text
}
print("decimal", decimal)
return
}
This will print
decimal 0.05
decimal 0.5
decimal 5
decimal 50.05