Current and Updating time in iOS?

i'm developing a tool for car driving which saves GPS Data, Accelerometer Data and Time for later use.

Acceleration is the least Priority, though.

All i need is a little code example so i can get the current system time printed as an updating clock in Xcode because i want it to save my data as fast and as often as possible :>

Thanks in advance for any answers :)

h4wkeye