Hi. Im new to iPhone development (or C based development) and im having some trouble understanding how the UIPicker works. I have downloaded the UICatalog code and im trying to find where the background of the picker is defined (you know, the white wheels).

Im used to web development, and my logic says that there is an image of an empty wheel somewhere and that image is chosen to be the background of the picker. I would like to change this image for a custom dark solid color. Is there any way to do this? If you could point at the part of the code that i have to look at it would be great! =)