freeing memory in a simple avaudioengine program? - objective-c

Question

I'm wondering how to free memory in this simple program that plays a file through a buffer and then stops it.
-(void)setupAudioOne
{
NSError *error;
BOOL success = NO;
_player = [[AVAudioPlayerNode alloc] init];
NSURL *hiphopOneURL = [NSURL fileURLWithPath:[[NSBundle mainBundle] pathForResource:#"Hip Hop 1" ofType:#"caf"]];
AVAudioFile *hiphopOneFile = [[AVAudioFile alloc] initForReading:hiphopOneURL error:&error];
_playerLoopBuffer = [[AVAudioPCMBuffer alloc] initWithPCMFormat:[hiphopOneFile processingFormat] frameCapacity:(AVAudioFrameCount)[hiphopOneFile length]];
success = [hiphopOneFile readIntoBuffer:_playerLoopBuffer error:&error];
_engine = [[AVAudioEngine alloc] init];
[_engine attachNode:_player];
AVAudioMixerNode *mainMixer = [_engine mainMixerNode];
AVAudioFormat *stereoFormat = [[AVAudioFormat alloc] initStandardFormatWithSampleRate:44100 channels:2];
[_engine connect:_player to:mainMixer fromBus:0 toBus:0 format:stereoFormat];
[self startEngine];
}
Above is the general setup of the engine and the player node.
Then we implement the player with a play button:
- (IBAction)play:(id)sender {
if (!self.playerIsPlaying)
{
[self setupAudioOne];
[_player scheduleBuffer:_playerLoopBuffer atTime:nil options:AVAudioPlayerNodeBufferLoops completionHandler:nil];
[_player play];
}
}
And finally we stop the player with a stop button:
- (IBAction)stopHipHopOne:(id)sender {
if (self.playerIsPlaying) {
[_player stop];
}
playerIsPlaying is just a simple BOOL that determines if the _player is playing.
So basically my question is, when you hit the stop button as this program is written now, no memory will be freed.
Surely there is a simple line of code that I can add to the stop button that frees up the memory the engine and player is using?
Any thoughts?

Answer 1

Yes, there is. After stopping the player node, you can call:
[_engine disconnectNodeInput:_player];
[_engine detachNode:_player];
I saw you're also keeping a reference to the audio buffer, so you might want to nil that one as well. Let me know if that doesn't work for you. Something else could be leaking.