Extension for UIApplication that allows capturing Volume Button events in Swift

UIApplication+VolumeButtons.swift

//
//  UIApplication+VolumeButtons.swift
//
//  Based on https://stackoverflow.com/a/70815088
//

import UIKit

// Stub protocol to allow us to call private methods
@objc private protocol UIApplicationPrivate {
    @objc func setWantsVolumeButtonEvents(_:Bool)
}

extension UIApplication {
    /**
     Capture volume button events.
     
     Enabling this setting will temporarily disable system-default volume button functionality,
     and sends the relavent notifications to the `default` notification center.
     
     - Parameter enabled: Enable or disable capturing of volume button events
     */
    public func setWantsVolumeButtonEvents(_ enabled: Bool) {
        let application = unsafeBitCast(self, to: UIApplicationPrivate.self)
        application.setWantsVolumeButtonEvents(enabled)
    }
}

extension UIApplication {
    /// Volume up button was pressed.
    public static let volumeUpButtonDownNotification: NSNotification.Name = NSNotification.Name("_UIApplicationVolumeUpButtonDownNotification")
    /// Volume up button was released.
    public static let volumeUpButtonUpNotification: NSNotification.Name = NSNotification.Name("_UIApplicationVolumeUpButtonUpNotification")
    /// Volume down button was pressed.
    public static let volumeDownButtonDownNotification: NSNotification.Name = NSNotification.Name("_UIApplicationVolumeDownButtonDownNotification")
    /// Volume down button was released.
    public static let volumeDownButtonUpNotification: NSNotification.Name = NSNotification.Name("_UIApplicationVolumeDownButtonUpNotification")
}