SpriteKit - How to stop a sound when enemy is killed - audio

Question

I'm building my first project with SpriteKit, but I can't figure out this part.
My project includes enemy helicopters flying into the screen. Each enemy plays a sound file around 14 seconds long. It's not a loop. It includes the sound of the enemy approaching before it enters the screen and more sound fx while it moves across the screen. The problem is that when I kill one of this helicopters, the sound keeps playing even after the enemy helicopter node has been removed from the scene.
I tried using the playSoundFileNamed action but I know those can't be stopped.
I tried using SoundManager but since all the enemies have the same file id, if I stop one, it stops all of them, even the ones still on the screen.
I read I should use OpenAL but I can't find a source that explains how can I add some kind of ID to each sound playing to know which one to stop.
Same with AVAudioPlayer. I tried creating a player for each enemy but for some reason the runBlock SKAction just ignores this code and never plays the sound. Weird. I also read AVAudioPlayer is better for playing background music than with handling sound FX.
Is there some kind of sound engine that helps with this issue?

Answer 1

I was able to solve it keeping all the audio players in an array. Here's the code:
First you create a NSMutableArray to keep track off all the players (called it 'playerArray'). Then each SKSpriteNode gets it's own player when they're added to the scene:
NSError *error;
NSURL * backgroundSound = [[NSBundle mainBundle] URLForResource:#"coptersound" withExtension:#"mp3"];
AVAudioPlayer *copterPlayer = [[AVAudioPlayer alloc] initWithContentsOfURL:backgroundSound error:&error];
copterPlayer.numberOfLoops = 1;
copterPlayer.delegate = self;
[copterPlayer prepareToPlay];
SKAction *moveCopter = [SKAction moveToX:(-10 - enemy.size.width) duration:14];
SKAction *copterSound = [SKAction runBlock:^{
[playerArray addObject:copterPlayer];
[copterPlayer play];
[enemy.userData setValue:copterPlayer forKeyPath:#"player"];
}];
SKAction *moveGroup = [SKAction group:#[copterSound, moveCopter]];
Then when collision is detected, this is how I stop the player:
[[enemy.userData objectForKey:#"player"] stop];
[playerArray removeObject:[enemy.userData objectForKey:#"player"]];
Need to pause all the players? Do this:
for(AVAudioPlayer *a in playerArray) {
[a pause];
}
And don't forget to remove all the players that have finished playing from the array using this:
- (void)audioPlayerDidFinishPlaying:(AVAudioPlayer *)player successfully:(BOOL)flag {
[playerArray removeObject:player];
}
Not sure if it's the best way but it works perfectly. Still open for better suggestions since it's my first time working with SpriteKit.

Answer 2

playSoundWithFile can be stopped, add a child SKNode to your helicopter, play the sound on your child, then just pause the child