title: get NSDate today, yesterday, this Week, last Week, this Month, last Month... variables
body: <p>I am trying to do is to get NSDate today, yesterday, this Week, last Week, this Month, last Month variables ready for comparison for headers to be added on UITableView's titleForHeaderInSection</p>
  
  <p>What I want is done manually in the code below for date 2009-12-11</p>
  
  <pre><code> NSDate *today = [NSDate dateWithString:@"2009-12-11 00:00:00 +0000"];
   NSDate *yesterday = [NSDate dateWithString:@"2009-12-10 00:00:00 +0000"];
   NSDate *thisWeek = [NSDate dateWithString:@"2009-12-06 00:00:00 +0000"];
   NSDate *lastWeek = [NSDate dateWithString:@"2009-11-30 00:00:00 +0000"];
   NSDate *thisMonth = [NSDate dateWithString:@"2009-12-01 00:00:00 +0000"];
   NSDate *lastMonth = [NSDate dateWithString:@"2009-11-01 00:00:00 +0000"];
  </code></pre>