MPVolumeView

Use a volume view to present the user with a slider control for setting the system audio output volume, and a button for choosing the audio output route. When first displayed, the slider’s position reflects the current system audio output volume. As the user drags the slider, the changes update the volume view. If the user presses the device volume buttons while sound is playing, the slider moves to reflect the new volume.

If there’s an Apple TV or other AirPlay-enabled device in range, the route button allows the user to choose it. If there’s only one audio output route available, the route button isn’t displayed.

Use this class by embedding an instance of it in your view hierarchy. The following code snippet assumes you’ve placed an instance of the UIView class on a view using Interface Builder, sizing and positioning it as desired to contain the volume view. Point to the UIView instance with an outlet variable—named, in the case of this example, mpVolumeViewParentView. You’d typically place code like that shown in Listing 1 in your viewDidLoad method.

parentView.backgroundColor = .clear
let volumeView = MPVolumeView(frame: parentView.bounds)
parentView.addSubview(volumeView)

When an audio output route that doesn’t support volume control, such as a car head unit, is active, the volume slider is replaced with the route name.

To instead display a volume slider as an alert, use the functions described in Global Volume Setting Methods.

The volume slider is a UISlider object. Sliders are always displayed as horizontal bars and an indicator, or thumb, notes the current value of the slider and can be moved by the user to change the setting.

Slider controls draw the volume slider track using two distinct images, which are customizable. The region between the thumb and the end of the track associated with the slider’s minimum value is drawn using the minimum volume slider image. The region between the thumb and the end of the track associated with the slider’s maximum value is drawn using the maximum volume slider image. Assigning different images to each state lets you customize the appearance of the slider when it is enabled, disabled, highlighted, and so on.

You can also customize the volume thumb image for the slider.