how can i implement a meter just like analog sound meter?

I need to implement a meter just like sound meter for my iPhone a开发者_StackOverflow社区pp ,but I am little bit confuse about its implementation. Please help how can I implement it?

The source code for the Android sound recorder's VU Meter is available online and should get you started.

You may use OpenGL based simple and easily extensible data visualization framework gl-data-visualization-view to display UV meter. You should just add GLDataVisualizationView, set visualization type as VU meter and set value to visualize. There are also iPhone sample project which shows how to use framework.