objective c - How to find the car speed on iPhone? -

i want find car speed on iphone when driving should use , how? core motion or core location? there documentation or sample code?

hey - you'll want core location this.

there tutorial here - http://www.vellios.com/2010/08/16/core-location-gps-tutorial/ followed once. there whole series 1 shows how calculate position , speed of device. there sample project download too. hope helps!