AudioServicesCreateSystemSoundID only once in application and play sound from anywhere - ios

Question

I am doing following stuff to play a sound on button tap. But here, I guess it loads sound file every time I tap on button.
if let soundURL = NSBundle.mainBundle().URLForResource("notification", withExtension: "mp3") {
var mySound: SystemSoundID = 0;
AudioServicesCreateSystemSoundID(soundURL, &mySound);
AudioServicesPlaySystemSound(mySound);
}
What I am trying to do is to load above code once in AppDelegate and call below code from any other VC :
let systemSoundID: SystemSoundID = 0;
AudioServicesPlaySystemSound(systemSoundID);
each time I want a sound.
But it causes an error in console showing
Failure to setup sound, err = -50.
Any Solution?

Answer 1

Rather than add to AppDelegate, it may be neater to add a separate class. This works for me:
import AudioToolbox
class PlaySound {
static private var mySound:SystemSoundID = {
// Do it like this so mySound is initialised only when it is first used
var aSound:SystemSoundID = 1000 // a default sound in case we forget the sound file
if let soundURL = NSBundle.mainBundle().URLForResource("Detection", withExtension: "wav") {
AudioServicesCreateSystemSoundID(soundURL, &aSound)
print("Initialised aSound:\(aSound)")
} else {
print("You have forgotten to add your sound file to the app.")
}
return aSound // this value is put into mySound when mySound is first used.
}()
static func play() { AudioServicesPlaySystemSound(mySound) } // play the sound
static func prepare() -> SystemSoundID { return mySound } // call this to preload sound to avoid any delay on first use, if you want
}
Then whenever I need the sound, I write
PlaySound.play()
and that only sets up the sound once, the first time it is used. The print above shows just when, and how many times, it is initialized. If you want to avoid any possibility of delay in setting up the sound when it is first used, you can call
PlaySound.prepare()
in AppDelegate when the app is launched.