iOS transparent window / alert / box overlay that shows loading message

is there a specific class for displaying a transparent loading box / alert / window, or are people constructing these loading message boxes from UIWindow class?

Here is a picture of what I am talking about. I am specifically referring to the transparent box / window in the picture that states, "Reloading Data" I have seen other apps use this type of transparent overlay, and was wondering there was a class for this specific type of window / alert. When one presses the volume button a similar overlay box appears.

enter image description here

Solution

I think you can see this : MBProgressHud