Can I observer system notifications like UIApplicationVolumeUpButtonDownNotification to surpass Apple app review process

Hi,

In my app, I need to capture images using camera. But I need to capture multiple images at a time.

So I have created custom camera controls to capture photos.

I have set UIImagePickerController's, showsCameraControls to NO.

With this I am able to capture images using camera, but I am unable to use volume buttons to capture images like system's default camera app.

I found that we can observe system notifcation :

_UIApplicationVolumeUpButtonDownNotification at

https://stackoverflow.com/questions/9109353/how-to-take-a-photo-on-the-volume-up-event-when-using-uiimagepickercontroller-wi

Now I just want to know if Apple will accept the app in App Review process if app is observing _UIApplicationVolumeUpButtonDownNotification and _UIApplicationVolumeDownButtonDownNotification.

If Apple rejects, I also want to know what does WhatsApp use, as they are using custom controls to capture photos, with the use of volume buttons to capture images.