title: NSDate change time zone
body: <p>I am writing an app that involves time zone. I want to grab the user's device time, lets call that <code>dateA</code>, and I have a target date that will always be in EDT time zone (<code>dateB</code>).  </p>
  
  <p>I want to get the difference between the 2 dates and show the user, but in <code>dateB</code>'s time zone.</p>
  
  <p>eg:<br>
  user device time is 07:30AM PDT, and <code>dateB</code> is 11:00AM EDT.<br>
  So the time difference would be 30 minutes.</p>
  
  <p>My algorithm is:<br>
  1) Get user device time<br>
  2) convert to EDT<br>
  3) grab the time difference between <code>dateA</code> and <code>dateB</code></p>
  
  <p>My issue is, after I get the user's device time <code>[NSDate date]</code>, and go through <code>DateFormatter</code> with timezone EDT.  The time does not change.</p>
  
  <p>EDIT::</p>
  
  <pre><code>    NSDate *localDate = [NSDate date]; //this will have 7:30AM PDT
      NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
      dateFormatter.dateFormat = @"yyyy-MM-dd HH:mm:ss";
      [dateFormatter setTimeZone:[NSTimeZone timeZoneWithName:@"EDT"]];
      NSString *convertedTimeString = [dateFormatter stringFromDate:localDate];
  </code></pre>
  
  <p>How come the convertedTimeString does not contain 10:30AM in EDT?
  What am I doing wrong?</p>