Customizing UISlider look

Question

To customize the visual look of a UISlider you can set the thumb and track images. Part of the track images gets stretched to the appropriate with. From the documentation:

Answer 1

You need to initialize your image with stretchableImageWithLeftCapWidth:topCapHeight:. leftCapWidth and topCapHeight are read-only properties on image objects, but using that function you can set them. You only set the left and top because the left and right caps are the same size, and the top and bottom are also the same. So, to use a custom slider track with a left side size of 5 pixels, you need to have an image of 11 pixels wide, by whatever height you need: 5 for the left cap, 1 pixel wide that is stretched for the track, and 5 more for the right. Having not played with it, I don't know if using a topCapHeight greater than 0 works as expected, but I suspect it wouldn't cause a great deal of problems.