得到当前的年,月,周的第一天和最后一天

////  EBDate.h//  ChargeMoney////  Created by eagle on 15-3-24.//  Copyright (c) 2015年 EagleB. All rights reserved.//#import <Foundation/Foundation.h>@interface EBDate : NSObject/** *  得到这个周的第一天和最后一天 */+(NSArray *)getFirstAndLastDayOfThisWeek;/** *  得到这个月的第一天和最后一天 */+(NSArray *)getFirstAndLastDayOfThisMonth;/** *  得到今天的第一天和最后一天 */+(NSArray *)getFirstAndLastDayOfThisYear;@end复制代码复制代码////  EBDate.m//  ChargeMoney////  Created by eagle on 15-3-24.//  Copyright (c) 2015年 EagleB. All rights reserved.//#import "EBDate.h"@implementation EBDate+(NSArray *)getFirstAndLastDayOfThisWeek{    NSCalendar *calendar = [NSCalendar currentCalendar];    NSDateComponents *dateComponents = [calendar components:NSWeekdayCalendarUnit | NSDayCalendarUnit | NSMonthCalendarUnit | NSYearCalendarUnit fromDate:[NSDate date]];    NSInteger weekday = [dateComponents weekday];   //第几天(从sunday开始)    NSInteger firstDiff,lastDiff;    if (weekday == 1) {        firstDiff = -6;        lastDiff = 0;    }else {        firstDiff =  - weekday + 2;        lastDiff = 8 - weekday;    }    NSInteger day = [dateComponents day];    NSDateComponents *firstComponents = [calendar components:NSWeekdayCalendarUnit | NSDayCalendarUnit | NSMonthCalendarUnit | NSYearCalendarUnit fromDate:[NSDate date]];    [firstComponents setDay:day+firstDiff];    NSDate *firstDay = [calendar dateFromComponents:firstComponents];        NSDateComponents *lastComponents = [calendar components:NSWeekdayCalendarUnit | NSDayCalendarUnit | NSMonthCalendarUnit | NSYearCalendarUnit fromDate:[NSDate date]];    [lastComponents setDay:day+lastDiff];    NSDate *lastDay = [calendar dateFromComponents:lastComponents];    return [NSArray arrayWithObjects:firstDay,lastDay, nil];}+(NSArray *)getFirstAndLastDayOfThisMonth{    NSCalendar *calendar = [NSCalendar currentCalendar];    NSDate *firstDay;    [calendar rangeOfUnit:NSMonthCalendarUnit startDate:&firstDay interval:nil forDate:[NSDate date]];    NSDateComponents *lastDateComponents = [calendar components:NSMonthCalendarUnit | NSYearCalendarUnit |NSDayCalendarUnit fromDate:firstDay];    NSUInteger dayNumberOfMonth = [calendar rangeOfUnit:NSDayCalendarUnit inUnit:NSMonthCalendarUnit forDate:[NSDate date]].length;    NSInteger day = [lastDateComponents day];    [lastDateComponents setDay:day+dayNumberOfMonth-1];    NSDate *lastDay = [calendar dateFromComponents:lastDateComponents];    return [NSArray arrayWithObjects:firstDay,lastDay, nil];}+(NSArray *)getFirstAndLastDayOfThisYear{    //通过2月天数的改变，来确定全年天数    NSDateFormatter *formatter = [[NSDateFormatter alloc] init];    [formatter setTimeZone:[NSTimeZone systemTimeZone]];    [formatter setDateFormat:@"yyyy"];    NSString *dateStr = [formatter stringFromDate:[NSDate date]];    dateStr = [dateStr stringByAppendingString:@"-02-14"];    [formatter setDateFormat:@"yyyy-MM-dd"];    NSDate *aDayOfFebruary = [formatter dateFromString:dateStr];        NSCalendar *calendar = [NSCalendar currentCalendar];    NSDate *firstDay;    [calendar rangeOfUnit:NSYearCalendarUnit startDate:&firstDay interval:nil forDate:[NSDate date]];    NSDateComponents *lastDateComponents = [calendar components:NSMonthCalendarUnit | NSYearCalendarUnit | NSDayCalendarUnit fromDate:firstDay];    NSUInteger dayNumberOfFebruary = [calendar rangeOfUnit:NSDayCalendarUnit inUnit:NSMonthCalendarUnit forDate:aDayOfFebruary].length;    NSInteger day = [lastDateComponents day];    [lastDateComponents setDay:day+337+dayNumberOfFebruary-1];    NSDate *lastDay = [calendar dateFromComponents:lastDateComponents];        return [NSArray arrayWithObjects:firstDay,lastDay, nil];}@end