Swift NSSound plays silently?

Question

I've done a bit of Swift and a fair amount of Objective-C on iOS, but basically no real OS X programming, so I haven't used NSSound. I was trying to help someone on a Swift forum, and ... it's not working. I'm not sure why.

In a playground, Swift REPL or even a script (#!/usr/bin/env swift), I can instantiate an NSSound successfully:

NSSound(named:"Hero")

In REPL / Playground or printing from the script, I can see that the optional has an NSSound inside. But when I call play(), I don't hear anything:

NSSound(named:"Hero")!.play()

Why?

This is a very small piece of code, it seems pretty simple, but obviously I'm missing something. It's not a big deal because it's not code that I need, but it's bugging me because it seems so simple and yet it's not working.

Answer 1

NSSound plays its sound asynchronously. By default, a playground exits immediately after executing the its code, so the process terminates before the sound has had a chance to play.

Here's a quick and dirty way to keep the playground alive indefinitely so that you can hear the sound play.

import Cocoa
import XCPlayground

if let sound = NSSound(named:"Hero") {
    XCPlaygroundPage.currentPage.needsIndefiniteExecution = true
    sound.play()
}

Answer 2

It seems as if NSSound, being a cocoa class, doesn't work properly in any of the environments I had tested:

• Playground
• Swift Script
• Swift REPL

If I put the same tiny piece of code in a skeleton OS X app, works fine.

Thanks to @Leo for pushing me to actually try it. I'd considered the possibility, but hadn't tried it until he suggested it.