FocusedValue and FocusedBinding (SwiftUI)

@FocusedValue reads a value published by whichever view currently has focus, the way @Environment reads shared values. The classic use is a macOS main-menu command that acts on the focused editor's content.

Publishing a Focused Value

Define a FocusedValueKey and register it on FocusedValues. The property must be optional: SwiftUI sets it to nil when no matching view has focus.

struct FocusedNoteValue: FocusedValueKey {
  typealias Value = String
}

extension FocusedValues {
  var noteValue: FocusedNoteValue.Value? {
    get { self[FocusedNoteValue.self] }
    set { self[FocusedNoteValue.self] = newValue }
  }
}

The focused view publishes with the focusedValue modifier, and any other view observes it.

struct NoteEditor: View {
  @State private var note = "text"

  var body: some View {
    TextEditor(text: $note)
      .focusedValue(\.noteValue, note)
  }
}

struct NotePreview: View {
  @FocusedValue(\.noteValue) var note

  var body: some View {
    Text(note ?? "Note is not focused")
  }
}

Use focusedSceneValue instead when the reader lives in a different scene, such as a menu command. For an ObservableObject rather than a value, the pair is focusedObject and @FocusedObject (scene variant focusedSceneObject).

Writing Back With FocusedBinding

@FocusedValue is read-only. To mutate the focused content, publish a Binding as the focused value and read it with @FocusedBinding.

struct FocusedNoteBinding: FocusedValueKey {
  typealias Value = Binding<String>
}

// NoteEditor publishes the binding:
TextEditor(text: $note)
  .focusedValue(\.noteBinding, $note)

struct NoteFormatter: View {
  @FocusedBinding(\.noteBinding) var note

  var body: some View {
    VStack {
      Text(note ?? "Note is not focused")
      Button("Clear note") { note = "" }
    }
  }
}

Assigning through the wrapper writes straight into the focused editor's state. Everything here goes nil the moment focus leaves, so always handle the unfocused case.