title: Why can't I use variableHeightRows in three20?
body: <p>In my <code>TTTableViewController</code> subclass, I'm setting <code>variableHeightRows = YES</code>. In my <code>TTTableViewCell</code> subclass, I've implemented</p>
  
  <p><code>+ (CGFloat)tableView:(UITableView*)tableView rowHeightForObject:(id)object</code></p>
  
  <p>The cell height is not varying at all, and Three20 doesn't even appear to be calling the rowHeightForObject method - I set a breakpoint inside it and during debugging it never hit my breakpoint. What am I doing wrong? Is there something else I need to set?</p>