title: NSDateFormatter doesn't convert my NSString in NSDate
body: <p>I have a string and need convert it to a date, but it doesn't convert correctly. I don't know why... my code is:</p>
  
  <pre><code>NSString * fecha = @"2011-12-07 11:11:29.657";
  
  NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
  [dateFormatter setDateFormat:@"yyyy-MM-dd HH:mm:ss.ZZZ"];
  
  NSDate *dateFromString = [[NSDate alloc] init]; 
  dateFromString = [dateFormatter dateFromString:fecha]; 
  
  NSCalendar *calendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
  unsigned units = NSYearCalendarUnit | NSMonthCalendarUnit |  NSDayCalendarUnit | NSHourCalendarUnit | NSMinuteCalendarUnit | NSSecondCalendarUnit;
  
  NSDateComponents *components = [calendar components:units              
                                             fromDate:dateFromString];
   NSInteger* hour = [components hour];
   NSInteger* minute = [components minute];
   NSInteger* second = [components second];  
  
  NSLog(@"Fecha: %@",fecha);
  NSLog(@"Format: %@",dateFormatter.dateFormat);
  NSLog(@"date: %@",dateFromString);
  </code></pre>
  
  <p>In my log:</p>
  
  <pre><code>2011-12-07 11:36:11.750 Catalogo-V1[13741:207] Fecha: 2011-12-07 11:11:29.657
  2011-12-07 11:36:11.750 Catalogo-V1[13741:207] Format: yyyy-MM-dd HH:mm:ss.ZZZ
  2011-12-07 11:36:11.751 Catalogo-V1[13741:207] date: (null)
  </code></pre>