uislider: knob as background, bar as foreground - like a sidewindow from a car?

if i want to have a custom slider, that looks quiet like a side-window from a car in its behaviour.

so it has a graphical mask overlying. in the background the "window" may be dragged, so that the "glass" fills the whole mask - or in the other direction that the "glass" is not there anymore.

is it possible as a m开发者_如何学编程odified slider or do i have to make a whole new element ?

use UISlider property minimumvalueimage And maximumvalueimage. you add your glass image as minimumvalueimage and transparent image as maximumvalueimage this gives effect like slider window