can't draw fast enough to keep up with touchesMoved?
<p>I am trying to implement simple paint functionality in my iPhone app. I tried updating a bitmap with a bitmap brush, and I also tried <a href="http://www.ipodtouchfans.com/forums/showthread.php?t=132024" rel="nofollow">this tutorial</a>.  </p>

<p>Both methods have the same problem, even though the code is almost totally different. It happens only on the device - the simulator works fine.  </p>

<p>When I touch the screen and move my finger, the screen does not get updated. When I pause or lift my finger, then the screen gets updated. This is not a very good user experience!  </p>

<p>I tried calling drawRect from touchesMoved directly, but found that the drawing context (which I retrieve using UIGraphicsGetCurrentContext) is invalid for many of the calls, so painting the screen myself for every touchesMoved doesn't work.</p>

<p>Any ideas?  </p>

<p>Thanks for any help, this has been quite frustrating!  </p>

<p>Henning  </p>
