如何有效地在Cocoa中以秒为单位显示时间？

I want to display the time (including seconds) in an application in a text field, pretty simple. What I currently do is create a NSTimer that runs every 0.1 seconds that gets the system time and updates the text field. This seems like a terribly inefficient way to accomplish this. Is there a better way?I want to display the time (including seconds)