attributedTextFormattingDefinition(_:)

Declaration

nonisolated func attributedTextFormattingDefinition<D>(_ definition: D) -> some View where D : AttributedTextFormattingDefinition

Discussion

Applying a text formatting definition to a Text or TextEditor created using the init(_:) or init(text:selection:) initializer, respectively, makes sure that any content observable to the user adheres to the constraints of the formatting definition.

You can compose your own definition from an attribute scope and a series of AttributedTextValueConstraints:

// MyTextFormattingDefinition.swift

struct MyTextFormattingDefinition: AttributedTextFormattingDefinition {
    var body: some AttributedTextFormattingDefinition<
        AttributeScopes.SwiftUIAttributes
    > {
        ValueConstraint(
            for: \.underlineStyle,
            values: [nil, .single],
            default: .single)
        MyAttributedTextValueConstraint()
    }
}

// MyEditorView.swift

TextEditor(text: $text)
    .attributedTextFormattingDefinition(MyTextFormattingDefinition())

To manually enforce constraints, e.g. before serializing text contents, use the constrain(_:) method.