how to make a progress view like the one in KAYAK app

how to make a progress view like the one in KAYAK app

I wonder how to make a progress view that looks like the one in KAYAK app
(it's a travel app to search for flights and hotels), screenshot:

i dig into the resources of KAYAK app on a jailbroken iPhone and found the
following 3 images that construct this progress view:
progressbar-background@2x.png

progressbar-gradient@2x.png

progressbar-overlay@2x.png

giving that the progress view has a moving overlay images that moves
repeatedly along with the gradient image.
any ideas or sample code would be highly appreciated.