+ (void)preventSystemVolumePopup {
    // Prevent Audio-Change Popus
    MPVolumeView *volumeView = [[MPVolumeView alloc] initWithFrame:CGRectMake(-2000., -2000., 0.f, 0.f)];
    NSArray *windows = [UIApplication sharedApplication].windows;

    volumeView.alpha = 0.1f;
    volumeView.userInteractionEnabled = NO;

    if (windows.count > 0) {
       [[windows objectAtIndex:0] addSubview:volumeView];
    }
}

MPVolumeView *volView = [[MPVolumewView alloc] init];
[self.view addSubview:volView];
volView.hidden = YES;

- (void)viewDidLoad {
    // Add an MPVolumeView to my view
    self.volView = [[MPVolumewView alloc] init];
    [self.view addSubview:self.volView];
    self.volView.hidden = YES;
}

- (void)someButtonTouched {
    // Show the MPVolumeView (and hopefully hide the system overlay)
    self.volView.hidden = NO;
}

- (void)refreshVolumeView {
    [self.volView willMoveToSuperview:self];
    [self.volView didMoveToSuperview];
}

- (void)viewDidLoad {
    // Add an MPVolumeView to my view
    self.volView = [[MPVolumewView alloc] init];
    [self.view addSubview:self.volView];
    self.volView.hidden = YES;
}

- (void)someButtonTouched {
    // Show the MPVolumeView (and hopefully hide the system overlay)
    self.volView.hidden = NO;
    [self refreshVolumeView];  // <<< This line was added
}