title: Drawing in Objective-c (iOS)
body: <p>I develop an iOS app with user-drawing as one of its parts. I want to draw over a bitmap's context. This can be implemented in two ways:</p>
  
  <p>1) When drawing option is selected I create bitmap context. The context is closed only when the tool is deactivated. So it remains opened during drawing.</p>
  
  <p>2) Each time when user draws a line - I create new bitmap context, copy current drawing there (stored as image), add new lines and then close the context (and save new image, of course). So it remains opened during only concrete drawing operation.</p>
  
  <p>The first method needs bitmap context to be opened for a (potentially) long time, the second - repeats image (with current drawing) copying each time and spends resources for frequent context creating / releasing. Which way is better? Why?</p>