gistfile1.m

// static var to store shared date formatter
static NSDateFormatter *_formatter = nil;

@implementation NSDate (Extras)

// Simple comparison, create a string from today and date, see if they're the same
- (BOOL)isToday
{
  // Lazy load and cache formatter, date formatters are slow to init
  if (!_formatter)
  {
    _formatter = [[NSDateFormatter alloc] init];
    [_formatter setTimeStyle:NSDateFormatterNoStyle];
    [_formatter setDateStyle:NSDateFormatterShortStyle];
  }
  
  // Do stuff with formatter...
}

@end