.swift

func pushNotificationHandler(userInfo: Dictionary<AnyHashable,Any>) {
     // Parse the aps payload
    let apsPayload = userInfo["aps"] as! [String: AnyObject]

    // Play custom push notification sound (if exists) by parsing out the "sound" key and playing the audio file specified
    // For example, if the incoming payload is: { "sound":"tarzanwut.aiff" } the app will look for the tarzanwut.aiff file in the app bundle and play it
    if let mySoundFile : String = apsPayload["sound"] as? String {
        playSound(fileName: mySoundFile)
    }
}
    
// Play the specified audio file with extension
func playSound(fileName: String) {
    var sound: SystemSoundID = 0
    if let soundURL = Bundle.main.url(forAuxiliaryExecutable: fileName) {
        AudioServicesCreateSystemSoundID(soundURL as CFURL, &sound)
        AudioServicesPlaySystemSound(sound)
    }
}