title: how to group by day with core data?
body: <p>I have a Entity called <code>deal</code> and <code>deal</code> has a property called <code>date</code> which is the time this deal object inserted into the store.</p>
  
  <p>and one day may have several <code>deal</code>s.</p>
  
  <p>So I want count some data group by day, I want fetch <code>day</code>and <code>countofsomething</code><br>
  like:</p>
  
  <pre><code>2013-06-03 3
  2013-06-02 4
  </code></pre>
  
  <p>and I don't want to use <code>sectionPath</code> because it only put deals into section.</p>
  
  <p>I know I can have this done by have another property(type:string) like <code>dayOfTheDate</code> which is like <code>2013-06-03</code> in each object.</p>
  
  <p>btw, transient property don't seem to work in this situation</p>
  
  <p>Could you understand what I am looking for?</p>
  
  <p>Comment here so I can provide more detail</p>
  
  <p>Thanks all of you.</p>