Initializer

init(_:value:format:prompt:)

Creates a text field that applies a format style to a bound optional value, with a label generated from a title string.

Declaration 宣言 

init<S, F>(_ title: S, value: Binding<F.FormatInput?>, format: F, prompt: Text? = nil) where S : StringProtocol, F : ParseableFormatStyle, F.FormatOutput == String
Available when Label is Text. LabelがTextである時に利用可能です。

Parameters パラメータ

title

The title of the text field, describing its purpose.

value

The underlying value to edit.

format

A format style of type F to use when converting between the string the user edits and the underlying value of type F.FormatInput. If format can’t perform the conversion, the text field sets binding.value to nil.

prompt

A Text which provides users with guidance on what to type into the text field.

Discussion 議論

Use this initializer to create a text field that binds to a bound optional value, using a ParseableFormatStyle 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 format style can parse the text. If the format style can’t parse the input, the text field sets the bound value to nil.

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

The following example uses an optional Double as the bound currency value, and a FloatingPointFormatStyle.Currency instance to convert to and from a representation as U.S. dollars. As the user types, a View.onChange(of:_:) modifier logs the new value to the console. If the user enters an invalid currency value, like letters or emoji, the console output is Optional(nil).


@State private var label = "Currency (USD)"
@State private var myMoney: Double? = 300.0
var body: some View {
    TextField(
        label,
        value: $myMoney,
        format: .currency(code: "USD")
    )
    .onChange(of: myMoney) { newValue in
        print ("myMoney: \(newValue)")
    }
}

See Also 参照

Creating a Text Field with an Optional

init<F>(LocalizedStringKey, value: Binding<F.FormatInput?>, format: F, prompt: Text?)
Creates a text field that applies a format style to a bound optional value, with a label generated from a localized title string.
Available when Label is Text. LabelがTextである時に利用可能です。
init<F>(value: Binding<F.FormatInput?>, format: F, prompt: Text?, label: () -> Label)
Creates a text field that applies a format style to a bound optional value, with a label generated from a view builder.
Available when Label conforms to View. LabelがViewに準拠する場合に利用可能です。