title: Background color for UIActivityIndicatorView
body: <p>I am using UIActivityIndicatorView to showing user that there is something going on, let them wait. But UIActivityIndicatorView looks small, do not have background color, and not very obvious to the user. While in iPhone SDK's UIImagePickerController, it uses the similar mechanism, but with the black background as well as some text besides the indicator.</p>
  
  <p>I am wondering whether there is any existing component to do that task, or I have to implement my own class to perform that task.</p>
  
  <p>Any suggestion are highly welcome, thanks in advance.</p>