small delays/pause in animation

Hi all can anyone help me out with the solution to this problem...

I ha开发者_运维知识库ve a project where I have NSTimer fire about 20 times a sec and thus using only one image(loaded programatically)produces the same image on the iPhone screen about twenty times in a second and these images fall from the top of the screen to the bottom where they are removed(more or less simulating rain fall or rain droplets).

My problem is that looking at the animation, I noticed that there are very small delays and which looks like a break, pause or small vibrations. Thus the flow isn't smooth.

Can anyone help me with the solution please.

Thanks in advance

You can check the CADisplayLink class.

Just because you ask for a timer in the UI run loop to go off at a certain rate, doesn't mean you will get called at exactly that rate or at evenly spaced intervals. You should check the time and the elapsed time "dt" inside each timer callback, and change your animation position, y + dy * dt, etc., accordingly.

Timer's arn't designed to be used for animation.

The best thing to do, is to have a thread running in an infinite loop, where you check if it's time to animate again, or just always animate (giving you a higher frame rate), but using the time elapsed as a reference for the state you are drawing.

You really shouldn't be using a timer for this. Instead you should be using the built in UIView animation methods:

animateWithDuration:animations:
animateWithDuration:animations:completion:
animateWithDuration:delay:options:animations:completion: