text: //
  //  NSDate+RHCalendarAdditions.h
  //
  //  Created by Richard Heard on 4/07/12.
  //  Copyright (c) 2012 Richard Heard. All rights reserved.
  //
  //  Redistribution and use in source and binary forms, with or without
  //  modification, are permitted provided that the following conditions
  //  are met:
  //  1. Redistributions of source code must retain the above copyright
  //  notice, this list of conditions and the following disclaimer.
  //  2. Redistributions in binary form must reproduce the above copyright
  //  notice, this list of conditions and the following disclaimer in the
  //  documentation and/or other materials provided with the distribution.
  //  3. The name of the author may not be used to endorse or promote products
  //  derived from this software without specific prior written permission.
  //
  //  THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  //  IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  //  OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  //  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  //  INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  //  NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  //  DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  //  THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  //  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  //  THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  //
  
  #import <Foundation/Foundation.h>
  
  @interface NSCalendar (RHCalendarAdditions)
  
  +(NSCalendar*)gregorianCalendar;
  
  @end
  
  
  @interface NSDate (RHCalendarAdditions)
  
  //components
  -(NSDateComponents*)componentsForGregorianCalendar;
  
  //seconds
  -(NSDate*)dateByAddingSeconds:(NSInteger)seconds;
  -(NSInteger)secondsBetweenDates:(NSDate*)otherDate;
  
  //days
  -(NSDate*)dateByAddingDays:(NSInteger)days;
  -(NSInteger)daysBetweenDates:(NSDate*)otherDate;
  
  -(NSDate*)previousDay;
  -(NSDate*)nextDay;
  
  //months
  -(NSDate*)dateByAddingMonths:(NSInteger)months;
  
  -(NSDate*)previousMonth;
  -(NSDate*)nextMonth;
  
  
  //normalization
  -(NSDate*)normalizedDate; //strips all time info.
  
  
  @end
  