Making an iPhone vibrate is very easy and takes only one function. The first thing you have to do is to import the AudioToolbox framework into your project and header file(s). That framework provides two functions you can use:

AudioServicesPlayAlertSound(kSystemSoundID_Vibrate);

When the device does not support vibration(e.g. an iPod touch), the device will beep instead of vibrating. If it supports vibration, it will vibrate.

AudioServicesPlaySystemSound(kSystemSoundID_Vibrate);

This function will vibrate a device that supports vibration. If the device¬†doesn’t support it, it will do nothing.