A slider is a horizontal track with a control called a thumb, which you can slide with your finger to move between a minimum and maximum value, such as screen brightness level or position during media playback. As a slider’s value changes, the portion of track between the minimum value and the thumb fills with color. A slider can optionally display left and right icons that illustrate the meaning of the minimum and maximum values.

The Brightness slider in Settings > Display & Brightness.

Customize a slider’s appearance if it adds value. A slider’s appearance, including track color, thumb image, and left and right icons, can be adjusted to blend with your app’s design and to communicate intent. A slider that adjusts image size, for example, could show a small image icon on the left and a large image icon on the right.

Don’t use a slider to adjust audio volume. If you need to provide volume control in your app, use a volume view, which is customizable and includes a volume-level slider and a control for changing the active audio output device. To learn about implementing a volume view, see MPVolumeView.

For developer guidance, see UISlider.