Audio manager with persistent muting

EYAudioManager.h

// erkanyildiz
// 20170815-2020+0900
//
// EYAudioManager.h

#import <Foundation/Foundation.h>
#import <AVFoundation/AVFoundation.h>
extern NSString * const EYAudioManagerMuteStateChangedNotification;

@interface EYAudioManager : NSObject <AVAudioPlayerDelegate>

@property (nonatomic, readonly) BOOL isMuted;

+ (instancetype)sharedInstance;
- (void)startBackgroundTheme:(NSString*)fileName;
- (void)mute;
- (void)unmute;
- (void)toggleMute;
- (void)playSound:(NSString *)fileName;

@end

EYAudioManager.m

// erkanyildiz
// 20170815-2020+0900
//
// EYAudioManager.m

#import "EYAudioManager.h"
#define EYAMUDKey_isMuted @"EYAudioManager_isMuted"

@interface EYAudioManager()

@property (nonatomic, strong) AVAudioPlayer* backgroundTheme;
@property (nonatomic, readwrite) BOOL isMuted;
@property (nonatomic, strong) AVAudioPlayer* player;
@end


@implementation EYAudioManager

NSString * const EYAudioManagerMuteStateChangedNotification = @"EYAudioManagerMuteStateChangedNotification";

+ (instancetype)sharedInstance
{
    static EYAudioManager * s_sharedInstance;
    static dispatch_once_t onceToken;
    dispatch_once(&onceToken, ^{ s_sharedInstance = EYAudioManager.new;});
    return s_sharedInstance;
}


- (id)init
{
    self = [super init];
    
    if(self)
    {
        self.isMuted = [NSUserDefaults.standardUserDefaults boolForKey:EYAMUDKey_isMuted];
    }
    
    return self;
}


- (void)startBackgroundTheme:(NSString*)fileName
{
    NSString* path = [NSBundle.mainBundle pathForResource:fileName.stringByDeletingPathExtension ofType:fileName.pathExtension];
    if (!path)
        return;

    [self.backgroundTheme stop];
    self.backgroundTheme = [AVAudioPlayer.alloc initWithContentsOfURL:[NSURL fileURLWithPath:path] error:NULL];
    self.backgroundTheme.numberOfLoops = -1;
    self.backgroundTheme.volume = self.isMuted?0.0:1.0;
    [self.backgroundTheme play];
}


- (void)mute
{
    self.isMuted = YES;
    [self saveStateAndPostNotification];
}


- (void)unmute
{
    self.isMuted = NO;
    [self saveStateAndPostNotification];
}


- (void)toggleMute
{
    self.isMuted = !self.isMuted;
    [self saveStateAndPostNotification];
}


- (void)saveStateAndPostNotification
{
    self.backgroundTheme.volume = self.isMuted?0.0:1.0;
    
    [NSNotificationCenter.defaultCenter postNotificationName:EYAudioManagerMuteStateChangedNotification
                                                      object:@(self.isMuted)
                                                    userInfo:nil];
    
    [NSUserDefaults.standardUserDefaults setBool:self.isMuted forKey:EYAMUDKey_isMuted];
    [NSUserDefaults.standardUserDefaults synchronize];
}


- (void)playSound:(NSString *)fileName
{
    if (self.isMuted)
        return;
    
    self.player = [AVAudioPlayer.alloc initWithContentsOfURL:[NSURL fileURLWithPath:[NSBundle.mainBundle pathForResource:fileName ofType:nil]] error:NULL];
    [self.player play];
}

@end