Minimal Quartz Composer Audio Player Plug In using AVAudioPlayer

BMPAudioFilePlayerPlugIn.h

#import <Quartz/Quartz.h>

@interface BMPAudioFilePlayerPlugIn : QCPlugIn

@property (nonatomic, copy) NSString *inputFilePath;

@end

#import "BMPAudioFilePlayerPlugIn.h"
#import <AVFoundation/AVFoundation.h>

#define	kQCPlugIn_Name				@"BMPAudioFilePlayer"
#define	kQCPlugIn_Description		@"BMPAudioFilePlayer description"

@interface BMPAudioFilePlayerPlugIn ()

@property (nonatomic, strong) AVAudioPlayer *audioPlayer;
@property (readonly) BOOL isPlaying;

@end

@implementation BMPAudioFilePlayerPlugIn

@dynamic inputFilePath;

+ (NSDictionary *)attributes
{
    return @{QCPlugInAttributeNameKey:kQCPlugIn_Name, QCPlugInAttributeDescriptionKey:kQCPlugIn_Description};
}

+ (NSDictionary *)attributesForPropertyPortWithKey:(NSString *)key
{
	// Specify the optional attributes for property based ports (QCPortAttributeNameKey, QCPortAttributeDefaultValueKey...).
    if ([key isEqualToString:@"inputFilePath"]) {
        return @{
                 QCPortAttributeNameKey: @"File Path",
                 QCPortAttributeDefaultValueKey: @"",
                 };
    } else {
        return nil;
    }
}

+ (QCPlugInExecutionMode)executionMode
{
	return kQCPlugInExecutionModeConsumer;
}

+ (QCPlugInTimeMode)timeMode
{
	return kQCPlugInTimeModeNone;
}

- (AVAudioPlayer *)audioPlayer {
    if (!_audioPlayer) {
        NSURL *url = [NSURL URLWithString:self.inputFilePath];
        NSError *error = nil;
        _audioPlayer = [[AVAudioPlayer alloc] initWithContentsOfURL:url fileTypeHint:AVFileTypeAppleM4A error:&error];
        
        if (error) {
            NSLog(@"%@", error.localizedDescription);
        }
    }
    return _audioPlayer;
}

@end

@implementation BMPAudioFilePlayerPlugIn (Execution)

- (BOOL)startExecution:(id <QCPlugInContext>)context
{
	return YES;
}

- (BOOL)execute:(id <QCPlugInContext>)context atTime:(NSTimeInterval)time withArguments:(NSDictionary *)arguments
{
    if (!self.isPlaying) {
        [self startPlaying];
    }

	return YES;
}

- (void)disableExecution:(id <QCPlugInContext>)context
{
    [self stopPlaying];
}

- (void)stopExecution:(id <QCPlugInContext>)context
{
    [self stopPlaying];
}

- (BOOL)isPlaying {
    return self.audioPlayer.isPlaying;
}

- (void)startPlaying {
    [self.audioPlayer play];
}

- (void)stopPlaying {
    [self.audioPlayer stop];
}

@end