iPhone開発 音楽が再生中か確認する

http://www.idevgames.com/forum/showthread.php?p=141850

BOOL			gOtherAudioIsPlaying = YES;

void CheckIfOtherAudioIsPlaying(void)
{
UInt32		propertySize, audioIsAlreadyPlaying;
AudioSessionInitialize(NULL, NULL, NULL, NULL);
// do not open the track if the audio hardware is already in use (could be the iPod app playing music)
propertySize = sizeof(UInt32);
AudioSessionGetProperty(kAudioSessionProperty_OtherAudioIsPlaying, &propertySize, &audioIsAlreadyPlaying);
if (audioIsAlreadyPlaying != 0)
{
	gOtherAudioIsPlaying = YES;
	//NSLog(@"other audio is playing");
	
	UInt32	sessionCategory = kAudioSessionCategory_AmbientSound;
	AudioSessionSetProperty(kAudioSessionProperty_AudioCategory, sizeof(sessionCategory), &sessionCategory);
	AudioSessionSetActive(YES);
}
else
{
	//NSLog(@"no other audio is playing ...");
	
	gOtherAudioIsPlaying = NO;
	
	// since no other audio is *supposedly* playing, then we will make darn sure by changing the audio session category temporarily
	// to kick any system remnants out of hardware (iTunes (or the iPod App, or whatever you wanna call it) sticks around)
	UInt32	sessionCategory = kAudioSessionCategory_MediaPlayback;
	AudioSessionSetProperty(kAudioSessionProperty_AudioCategory, sizeof(sessionCategory), &sessionCategory);
	AudioSessionSetActive(YES);
	
	// now change back to ambient session category so our app honors the "silent switch"
	sessionCategory = kAudioSessionCategory_AmbientSound;
	AudioSessionSetProperty(kAudioSessionProperty_AudioCategory, sizeof(sessionCategory), &sessionCategory);
}
}