how to bind to both nullable and nonnullable values in swiftui

Question

I have the following view, which works fine:


struct Decimal_text_field_nullable : View {
    @State var name : String
    @State var place_holder : String
    @Binding var value : Double?
    
    var format_as_decimal: NumberFormatter {
        let formatter = NumberFormatter()
        formatter.numberStyle = .decimal
        return formatter
    }
    
  
    
    var body: some View {
        VStack(alignment: .leading) {
            Text(name)
                .font(.headline)
            TextField( place_holder, value : $value, formatter: format_as_decimal )
                .add_close_button()
                .keyboardType(.decimalPad)
                .padding(.all)
                .background(Color(red: 239.0/255.0, green: 243.0/255.0, blue: 244.0/255.0, opacity: 0.2))
        }
        .padding(.horizontal, 15)
    }

however I have to have a Decimal_text_field_nullable and a Decimal_text_field with exactly the same code except for a question mark on the definition of value - because I can't bind a Double value to a Double? value.

Is there any way to make a decimal_text_field where this can work:

VStack()
{
    Decimal_text_field("non optional value", value = $non_nullable_double )
    Decimal_text_field("optional_value", value = $nullable_double )
}

Raja Kishan · Accepted Answer · 2021-07-05 09:23:38Z

1

You can use this approach for both bindings. This code used for both.

struct Decimal_text_field: View {
    @State private var name: String
    @State private var place_holder: String
    @Binding private var value: Double?
    
    init(name : String, place_holder : String, value : Binding<Double?>) {
        self.name = name
        self.place_holder = place_holder
        self._value = value
    }
    
    init(name : String, place_holder : String, value : Binding<Double>) {
        self.name = name
        self.place_holder = place_holder
        self._value = Binding(get: {Optional(value.wrappedValue)}, set: {value.wrappedValue = $0 ?? 0})
    }
    
    var format_as_decimal: NumberFormatter {
        let formatter = NumberFormatter()
        formatter.numberStyle = .decimal
        return formatter
    }
}

Note: Try to avoid under score on the var name and struct name.

answered Jul 5, 2021 at 9:23

Raja Kishan

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2 Comments

iSpain17 Over a year ago

Yes, this seems like the appropriate approach, creating two different inits for the two cases, and merging them behind the hood.

Darren Oakey Over a year ago

I thought of that - but was missing knowledge of that Binding( get:set:) - that's nice. Thanks!

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