Graphics Reference
In-Depth Information
}
}
@end
Figure 13.2
A sketch produced using the chalkboard drawing app
This performs reasonably well on the simulator, but is not great on a real device. The
problem is that we are redrawing every previous brush stroke each time our finger moves,
even though the vast majority of the scene hasn't changed. The more we draw, the slower it
gets, so the gap between each new stroke increases over time as the frame rate drops (see
Figure 13.3). How can we improve this performance?
