I tried the Blocker game in Chapter 6 on iPhone simulator, and on real, physical devices iPhone 4S and the New iPad. There is a phenomenon that, I see the ball moving about 3 pixels each time, but sometimes, it won't move for a split second, and then it moves for 5, 6 or 7 pixels, if feels like. So the movement is a bit jagged at times.

I don't see it happening in Angry Birds. Could it be the way how sub-view is rendered in the main view. Would the same issue be there if we use a "frame buffer" so we paint everything all at once? How can it be improved so that animation of the ball is very smooth?

I don't have the book with me but I think it's because they're using Quartz 2D for the example instead of Open GL ES that you would typically use for better performance.

I thought I remembered that the author indicated that somewhere as well but maybe that was another book I read.

It is actually using the sub-views to display the things on screen and adjust their offset. No drawRect is used to redraw everything but I wonder how smooth animations will be if using sub-views... can the animation be smooth... will every frame of the 60fps require redrawing everything (by iOS)?