Button for live microphone input out iphone speakers

I have a basic app, it's a college project and I need to create a button that you press to activate the microphone of the iphone and it feeds the audio live through the iphone speakers. (i understand there will be feedback but using headphones should be fine)! Anyway I'm just looking for the code to do this and a can apply it to my app. This is a quick and simple job. Any takers or advice? Thanking you!