If you want to increase the volume of iphone in a specific app and then reduce it to it's current volume. The following code might get helpful:- (NOTE:Include FrameWork: MediaPlayer.framework )

-(void)exampleFuctionSample{

NSLog(@"");

[self increaseVolume];

// Code

[NSTimer scheduledTimerWithTimeInterval:2.0 target:self selector:@selector(reduceVolumeToCurrent) userInfo:nil repeats:NO ]; // Timer will help you delay so that you can play increase volume

}

-(void)increaseVolume{

NSLog(@"Entered Set Volume");

float currentVolume=[MPMusicPlayerController applicationMusicPlayer].volume;

NSLog(@"Current volume is %f",[MPMusicPlayerController applicationMusicPlayer].volume);

float maxVolume = 1.0;

[[MPMusicPlayerController applicationMusicPlayer] setVolume:maxVolume];

}

-(void)reduceVolumeToCurrent{

NSLog(@"reduceVolumeToCurrent");

[[MPMusicPlayerController applicationMusicPlayer]setVolume:currentVolume];

}