Kiss FFT is a small and simple FFT library. It has no complicated platform-specific optimizations, can do either fixed or floating point with just a recompile, and is efficient enough for all but the most demanding applications.

大名鼎鼎的kiss fft算法，其中有针对浮点运算的优化，以及针对定点运算的优化,The famous kiss fft algorithm, which optimized for floating-point operations, as well as the optimal fixed-point computation

How to use kiss fft with the iPhone. Everything is displayed on the console

Kiss FFT library for Iphone