How to Calibrate Compass in iPhone 3GS?

I found a useful information for you, how to properly calibrate compass in iPhone 3GS? Yes, of course, you really want to know the answer. In fact, to calibrate compass in iPhone 3GS quite easy, not difficult. All you need to do is watch a short video below, I think you will be able to find a solution. You are able to move the iPhone around just like a mini car. Hopefully helpful.