title: Sectioned NSTableView using NSArrayController
body: <p>I'm trying to create a sectioned <code>NSTableView</code> using <code>NSArrayController</code> and cocoa bindings. I'm searching for a similar approach like with <code>NSFetchedResultsController</code> in iOS, where you can set a section key path. I want to make something similar with <code>NSArrayController</code>.</p>
  
  <p>I give you an example:
  I have different tasks. Each task has one of three different priorities, low, medium or high. The tasks also has attributes like title, description, date, etc. I want to section or group the tasks by priority (the section key path here is the priority). </p>
  
  <p>You can I solve this problem with bindings and <code>NSArrayController</code>? Do I need multiple <code>NSArrayController</code> or just one?</p>