SilentSwitchOverrider.h

#import <Foundation/Foundation.h>

@interface SilentSwitchOverrider : NSObject
@end

SilentSwitchOverrider.m

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

@interface SilentSwitchOverrider() {}
@property (nonatomic) AVAudioSession* audioSession;
@property (nonatomic) NSString* prevCategory;
@property (nonatomic) NSInteger prevOptions;
@end

@implementation SilentSwitchOverrider

- (id) init {
  self = [super init];
  if (self) {
    _audioSession = [AVAudioSession sharedInstance];
    _prevCategory = [_audioSession category];
    _prevOptions = [_audioSession categoryOptions];
    NSError *setCategoryError = nil;
    if (![_audioSession setCategory: AVAudioSessionCategoryPlayback
                        withOptions: AVAudioSessionCategoryOptionMixWithOthers
                              error: &setCategoryError]) {
      // handle error
    }
  }
  return self;
}

-(void) dealloc {
  NSError *setCategoryError = nil;
  if (![_audioSession setCategory: _prevCategory
                      withOptions: _prevOptions
                            error: &setCategoryError]) {
     // handle error
  }
}

@end