声音在AVAudioPlayer播放完成后执行操作？

I am using the AVAudioPlayer framework, and I have several sounds that play one at a time. When a sound is finished playing, I want the application to do something. I tried to use audioPlayerDidFinishPlaying to do the action at the end of the first sound, but I couldn't use that for the second sound because I got a redefinition error. Can I use NSTimeInterval to get the duration of a sound?I am using the AVAudioPlayer framework, and I h