flashing buttons/ indicators/uiimage??

[syd]

I wanted to have indictors flashing at metronome clicks. I was thinking maybe like a circular ball that goes green and red at different time intervals.
I would also need maybe a dozen of them at different parts on the screen.
Would i be able to accomplish this using a UIImage (png image) of 2 balls which has two different colors that i will have to draw at every time instant or would this be easier with quartz?
I would really appreciate it if anyone can help out with some pseudo code.

This is what i would want to to. At a metronome tick change the color of balls that would be in different positions of the screen. Also after the tick is over they should go back to their original colors.

Thanks a bunch

[Bertrand21]

what does this have to do with the 3.0 sdk?