Here's a simple version of what you're describing. It is "simple" in the sense that I didn't bother trying to add the shading and other subtleties. But it's easy to construct and you can tweak it to draw in a more subtle way if you like. For example, you could make your own image and use it as the slider's thumb. This is actually a UISlider subclass lying on top of a UIView subclass (MyTherm) that
