How to disable iOS System Sounds
Solution 1:
It is possible to change the system sounds, which turns out to be the ringer btw, using the AVSystemController. However, AVSystemController exists in the private Celestial framework. Since this framework is referenced by UIKit, it is still possible to use this class without directly referencing it.
Apple prohibits using private API's, so that alone makes this a bad idea. Given my circumstance, I think they may make an exception, BUT I will likely abandon this course since after taking it I realized that it didn't fix my problem. It does indeed mute the sounds, but as soon as I plug in to my accessory, the system sounds come out at max volume even though the ringer volume is set to 0. This leads me to believe the answer to solving my problem is in the MFI documentation.
Anyhow, here is how to change the ringer using private framework / api (which will get your app rejected without some kind of special permission).
short answer:
[[AVSystemController sharedAVSystemController] setVolumeTo:0 forCategory:@"Ringtone"];
answer without having to directly reference Celestial frameork / AVSystemController.h:
- (void) setSystemVolumeLevelTo:(float)newVolumeLevel
{
Class avSystemControllerClass = NSClassFromString(@"AVSystemController");
id avSystemControllerInstance = [avSystemControllerClass performSelector:@selector(sharedAVSystemController)];
NSString *soundCategory = @"Ringtone";
NSInvocation *volumeInvocation = [NSInvocation invocationWithMethodSignature:
[avSystemControllerClass instanceMethodSignatureForSelector:
@selector(setVolumeTo:forCategory:)]];
[volumeInvocation setTarget:avSystemControllerInstance];
[volumeInvocation setSelector:@selector(setVolumeTo:forCategory:)];
[volumeInvocation setArgument:&newVolumeLevel atIndex:2];
[volumeInvocation setArgument:&soundCategory atIndex:3];
[volumeInvocation invoke];
}
Solution 2:
Using MediaPlayer framework, we can set the level of SYSTEM sound
[[MPMusicPlayerController applicationMusicPlayer] setVolume:0];