How could Dan Briklin's Note Taker draw lines so smoothly?

I tried to write a similar hand drawing app. But the line drawing is always a little slow.

If you'd writte开发者_如何学运维n a similar app and got the line drawing optimized, please explain a bit.

Dan's Note Taker Lite.

I would try some of these settings.

Note the bottom setting of AllowAntialiasing.

CGContextBeginPath(context);
CGContextSetInterpolationQuality(context,  kCGInterpolationLow);
CGContextSetAllowsAntialiasing(context, true);