得到当前年、月、周的第一天和最后一天

话不多说，上代码

//

//  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

//

//  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

感谢这篇文章:http://my.oschina.net/yongbin45/blog/156181#OSC_h4_7