UIView animations and changing values as parameters animate

When I use the UIView animation methods such as UIView beginAnimations to ramp a value over a duration, does it actually ramp the value itself so that if I get the value I see it changing over time, or does it set the value to the final value and then simply visually display it ramping?

What I am seeing is that the value app开发者_JAVA技巧ears to get set immediately to its final value and attempts to read the value over the duration of the animation return the final value and not the linear interpolation of it.