How to detect heart pulse rate without using any instrument in iOS sdk?

Question

I am right now working on one application where I need to find out user\'s heartbeat rate. I found plenty of applications working on the same. But not able to find a single

Answer 1

Various DSP signal processing techniques can be used to possibly discern very low level periodic signals out of a long enough set of samples taken at an appropriate sample rate (accelerometer or reflected light color).

Some of the advanced math functions in the Accelerate framework API can be used as building blocks for these various DSP techniques. An explanation would require several chapters of a Digital Signal Processing textbook, so that might be a good place to start.