Pretty much what I am trying to do, is create the following image:

So this is a progress bar, which will show how many votes the client get in that option. How can I do that? I was wondering if I can use a mask (as I would in flex), but all the masking implementations that I found on the web are doing masks for UIImages, and not for UIImageView. I cannot do the mask in the UIImage, because the two images have the same dimensions. I have to use the X and Y of the images to crop them?! So, any suggestions?
Here are the two images that I have to create that progress bar:


Cheers.
you want to get rid of all of the same bit in the middle of each image.
then do something like: