Great Tutorial - Phase Offset

Great tutorial Ducky.  Your tutorials are always so well done it's great to see them on CGCookie.  Not sure this will help but while I was watching the explanation of phase offset I thought I might be able to give a little of the math that makes it work.  The reason your looping works with 2*pi or 4*pi (any even multiple of pi) goes back to why your rotation looping works with any multiple of 360.  In math, a phase offset is used to shift trig functions by a certain angle.  To make the math calculations easier the angle is measured in radians instead of degrees.  It turns out that 360 degrees is equal to 2*pi radians.  So any even multiple of pi is the same as a multiple of 360.  That's probably clear as mud but hope it helps someone that wanted to know.