title: Mimic Apple's UIViewAnimationOptionCurveEaseInOut math equation?
body: <p>I want to create an animation that will appear to animate just like Apple's CurveEaseInOut, so that my application looks consistent. The problem is that this particular animation cannot use the UIView animate method. I must manipulate the position manually at every frame. For example, I get a time T and I need to output the center C for the point at that time. Rather than using a linear relationship (e.g. C = T), I want it to ease in and out just like Apple does.</p>
  
  <p>Which curve equation is Apple using for that animation option?</p>
  
  <p>I assume the curve looks similar to this: (which was taken from <a href="https://stackoverflow.com/questions/1146281/cubic-curve-smooth-interpolation-in-c-sharp">this question</a>)</p>
  
  <p><img src="https://i.stack.imgur.com/J2x1M.jpg" alt="enter image description here"></p>
  
  <p>If that is the case, it looks like I should be able to just tweak the <a href="http://en.wikipedia.org/wiki/Cubic_Hermite_spline" rel="nofollow noreferrer">Cubic Hermite spline</a> equation with the correct constants and get the same result. The question is which constants does Apple use?</p>