How to create simple music visualizer of an iPhone app?

I want to make a simple drum machine app for iPhone.

Now I'm designing archichecture for it. After some research I've decided to stick with methods described in Apple's Audio Unit Hosting Guide for making playback system, these techniques are also presented in Audio Mixer sample and their complexity is pretty fit my current ingeneering knowledge. (Mixig C++ and Objective-C code and using OpenAl looks frightening)

But I'm stuck at figuring out, how will I make a simple music visualizer, I plan to do standard spectrum visualizer showing vertical bars representing intensities of different frequency components.

1. I can't decide what is better to use to analyze raw sound data, that I will feed to sound I/O module开发者_如何学Go, are there any Objective-C framework for that?

2. Also I don't know what type of graphic rendering to use? Can a simple visualizer be made using just Core Graphics or it is only a job for OpenGL? I want to achieve about 30 updates per second to make it look smooth?

Can you help me?

my suggestion is to exploit cocos2d http://www.cocos2d-iphone.org/ a very good framework enable developers to easily and quickly realize IOS graphical applications without dealing with OpenGL complexity.

You could for example create small png files representing rows of your FFT bins and animate them according to the music. This would be very easy with cocos2d because it already provides API to load png files and animate them.

bye