# Switch

> A setting that is on or off, in three sizes.

`ui.Switch` is a setting that takes effect at once. It holds no value: the app owns it and updates it in `OnChange`.

```go
notifications := core.NewSignal(cx, true)
ui.Switch{Checked: notifications.Get, OnChange: notifications.Set, Label: "Notifications"}
```

## Sizes

`ui.Switch` takes `Checked`, `OnChange`, `Label` and `Size` (`SizeDefault`, `SizeSmall` or `SizeLarge`). The knob slides and the track changes color on the platform's frame clock.

```go
ui.Switch{Checked: sync.Get, OnChange: sync.Set, Label: "Sync automatically", Size: ui.SizeSmall}
```

A switch is for a setting that applies at once. For a choice inside a form, use a [checkbox](https://nsgo.dev/docs/ui/checkbox.md); for one of several options, use `ui.Radio`s in a `ui.RadioGroup` or a [select](https://nsgo.dev/docs/ui/select.md).

## Accessibility

The switch reports `RoleSwitch` and its on or off state. `Label` is what assistive technology reads, and the text beside a switch is usually its label. Space or a press toggles it when it has the keyboard focus.

## Platform

The control is drawn by the app, so it looks the same everywhere. Presses, focus and the screen reader are the platform's. A phone's switch is the same size as a desktop's by design; `SizeSmall` is for dense rows, not for a device.

## Related

- [Checkbox](https://nsgo.dev/docs/ui/checkbox.md): one or more choices.
- [Forms](https://nsgo.dev/docs/forms.md): settings in a form.
- [Accessibility](https://nsgo.dev/docs/accessibility.md): labels and focus.
- The gallery's Switch page.
- [Unstyled components](https://nsgo.dev/docs/authoring/base.md#switch): `base.Switch`, for a switch of a look of your own.