title: Optimizing a drawing (with finger touches) application for iPhone SDK
body: <p>I'm writing an application that uses your finger to draw simple diagrams. I have it working for the most part but now I'm trying to optimize its performance. When the user swipes their finger fast, I can't capture enough touch events to draw a smooth path. </p>
  
  <p>Here's my current approach:</p>
  
  <p>1) I subclassed a UIView and added a poroperty to a CGLayer (gets created lazily and is the same size as my UIView).
  2) My UIView subclass responds to touch events by storing the current and last touch points in instance variables. 
  3) My view's setNeedsDisplay is called and in the draw rect , do the following:
  - draw a line from the previous touch location to the current touch location to the CGLayer
  - draw the entire CGLayer to my views context in one go</p>
  
  <p>The main problem is when a user swipes fast I get relatively few touch events, so the lines I draw between the touches are long and makes the path look jagged not smooth.</p>
  
  <p>My questions: </p>
  
  <p>1) Does drawRect (on my UIView subclass) and my touch event handlers on my UIView subclass get called in the same thread? I.e. could I have to threads executing (one in a touch event and the second in my draw rect)? </p>
  
  <p>If no - do touch events get queued up while drawRect is being called? And how can I improve performance - simply improve performance of drawRect?</p>
  
  <p>If yes - how can I get more touch events to happen so I can draw a smoother path? </p>
  
  <p>Thanks.</p>