title: iOS core data sum data by date, month year
body: <p>In iOS, I am trying to sum a core data field by day, month and year.I found some examples using <code>NSExpression</code>, but not this specific request.</p>
  
  <p>Here is my data object:</p>
  
  <pre><code>data{
    amount:NSNumber
    date:NSDate
  }
  </code></pre>
  
  <p>Looking to group the data by day, month, and year then sum the amounts.</p>
  
  <p>Thanks.</p>