CPSlider 是 UISlider 的改进版，is a drop-in, subclass replacement for UISlider that allows varying scrubbing speeds as the user drags away from the slider thumb, emulating the slider used in the iOS iPod music player. It also includes delegate callbacks to allow an object to be notified of scrubbing speed changes. 转载:http://www.adobex.com/ios/source/details/00000902.htm