Sound not playing in simulator, playing during debug in Xcode - swift

Question

I'm trying to face with the book "Intro to app development" by apple. I'm stuck on exercise AnimalSounds.
There is a SimpleSound class provided by the book, and our job is to use a sound object to reproduce a sound.
The simulator does not play any sound.
The audio files are in the build bundle and are found by the class.
I checked the simulator with other apps (e.g. youtube on safari) and sound works.
SimpleSound class (provided by example, not written by me)
import Foundation
import AudioToolbox
class SimpleSound {
private var soundID: SystemSoundID = 0
public init(named name: String) {
if let soundURL = soundURL(forName: name) {
let status = AudioServicesCreateSystemSoundID(soundURL as CFURL, &soundID)
if status != noErr {
print("Unable to create sound at URL: '\(name)'")
soundID = 0
}
}
}
public func play() {
if soundID != 0 {
print("Playing sound \(soundID)")
AudioServicesPlaySystemSound(soundID)
//AudioServicesPlaySystemSound(1001)
}
}
private func soundURL(forName name: String) -> URL? {
let fileExtensions = ["m4a", "wav", "mp3", "aac", "adts", "aif", "aiff", "aifc", "caf", "mp4"]
for fileExtention in fileExtensions {
if let soundURL = Bundle.main.url(forResource: name, withExtension: fileExtention) {
return soundURL
}
}
print("Unable to find sound file with name '\(name)'")
return nil
}
deinit {
if soundID != 0 {
AudioServicesDisposeSystemSoundID(soundID)
}
}
}
Code used in my viewController (written by me) in a button tapped action:
let meowSound = SimpleSound(named: "meow")
meowSound.play()
When debugging from Xcode line by line, when the function play() is invoked, the sound is reproduced. When app is running in simulator (with no debugging) or in actual iPhone sound does not play.
If standard system sound 1001 is uncommented, sound is played for both simulator and iPhone.
Any ideas?