Contents

init(_:value:formatter:)

Create an instance which binds over an arbitrary type, V.

Declaration

nonisolated init<S, V>(_ title: S, value: Binding<V>, formatter: Formatter) where S : StringProtocol

Parameters

  • title:

    The title of the text view, describing its purpose.

  • value:

    The underlying value to edit.

  • formatter:

    A formatter to use when converting between the string the user edits and the underlying value of type V. If formatter can’t perform the conversion, the text field doesn’t modify binding.value.

Discussion

Use this initializer to create a text field that binds to a bound optional value, using a Formatter to convert to and from this type. Changes to the bound value update the string displayed by the text field. Editing the text field updates the bound value, as long as the formatter can parse the text. If the format style can’t parse the input, the bound value remains unchanged.

Use the onSubmit(of:_:) modifier to invoke an action whenever the user submits this text field.

The following example uses a Double as the bound value, and a NumberFormatter instance to convert to and from a string representation. The formatter uses the NumberFormatter.Style.decimal style, to allow entering a fractional part. As the user types, the bound value updates, which in turn updates three Text views that use different format styles. If the user enters text that doesn’t represent a valid Double, the bound value doesn’t update.

@State private var myDouble: Double = 0.673
@State private var numberFormatter: NumberFormatter = {
    var nf = NumberFormatter()
    nf.numberStyle = .decimal
    return nf
}()

var body: some View {
    VStack {
        TextField(
            value: $myDouble,
            formatter: numberFormatter
        ) {
            Text("Double")
        }
        Text(myDouble, format: .number)
        Text(myDouble, format: .number.precision(.significantDigits(5)))
        Text(myDouble, format: .number.notation(.scientific))
    }
}

See Also

Creating a text field with a value