text: //
  //  NSCalendar+HGExtention.h
  //  UICollectionViewDemo
  //
  //  Created by 小雨很美 on 2017/5/15.
  //  Copyright © 2017年 小雨很美. All rights reserved.
  //
  
  #import <Foundation/Foundation.h>
  NS_ASSUME_NONNULL_BEGIN
  @interface NSCalendar (HGExtention)
  - (nullable NSDate *)hg_firstDayOfMonth:(NSDate *)month;
  - (nullable NSDate *)hg_lastDayOfMonth:(NSDate *)month;
  - (nullable NSDate *)hg_firstDayOfWeek:(NSDate *)week;
  - (nullable NSDate *)hg_lastDayOfWeek:(NSDate *)week;
  - (nullable NSDate *)hg_middleDayOfWeek:(NSDate *)week;
  - (NSInteger)hg_numberOfDaysInMonth:(NSDate *)month;
  @end
  NS_ASSUME_NONNULL_END
  