iPhone: Random moving bubbles animation using coregraphics?

I'm developing an app which will show 10-15 bubbles is moving around the screen randomly and will stay inside the screen. In fact they are buttons and when user will click on any-one it will show a random image.

Now my problem is, how should i animate smoothly these bubbles as random moving buttons? i have tried with timer and uiview animation but they are not working开发者_如何学Go well or i'm missing something.

Plz plz help me.....

Regards... Benzamin.

I would recommend Core Animation for your app.
The "Move Me" sample code does almost exactly what you need.

Apple also has a good introduction to CA over here.