防微信聊天时间生成

#import <Foundation/Foundation.h>

@interface ChatTimeUtil : NSObject
+(NSString *)showDate:(NSDate *)date upDate:(NSDate *)a;

//nsstring 转 nsdate
+ (NSDate *)dateFromString:(NSString *)dateString format:(NSString *)format;

+ (NSString *)stringFromDate:(NSDate *)date format:(NSString *)format;
@end

//
//  ChatTimeUtil.m
//  Test1111
//
//  Created by victor-lee on 14-12-11.
//  Copyright (c) 2014年 自由人. All rights reserved.
//

#import "ChatTimeUtil.h"


@interface ChatTimeUtil()
@end


@implementation ChatTimeUtil
//如果一个方法中，需要外部变量时，而且这个变量有生命周期时，就不能用工具类.
+(NSString *)showDate:(NSDate *)date upDate:(NSDate *)a{
    NSDate *tmpDate =[[NSDate alloc] initWithTimeIntervalSinceReferenceDate:([a timeIntervalSinceReferenceDate] + 5*60)];
    if([tmpDate earlierDate:date] == tmpDate){
        if([self isToday:date]){
            return  [ChatTimeUtil stringFromDate:date format:@"HH:mm"];
        }else{
            return  [self returnDate:date];
        }
    }else{
        return nil;
    }
}

//nsstring 转 nsdate
+(NSDate *)dateFromString:(NSString *)dateString format:(NSString *)format{
    NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
    [dateFormatter setDateFormat: format];
    NSDate *destDate= [dateFormatter dateFromString:dateString];
    return destDate;
}

//nsdate 转 nsstring
+(NSString *)stringFromDate:(NSDate *)date format:(NSString *)format{
    NSDateFormatter *dateFormatter = [[NSDateFormatter alloc] init];
    [dateFormatter setDateFormat:format];
    return [dateFormatter stringFromDate:date];
    
}

//如果日期是一星期内，便返回星期N，如果是一星期前就返回之间的日期
+(NSString *)returnDate:(NSDate *)d{
    NSDate *tmpDate =[[NSDate alloc] initWithTimeIntervalSinceReferenceDate:([[NSDate date] timeIntervalSinceReferenceDate] - 7*24*60*60)];
    
    if([tmpDate earlierDate:d] == tmpDate){
        
        NSDateComponents *componets = [[NSCalendar autoupdatingCurrentCalendar] components:NSWeekdayCalendarUnit fromDate:d];
        ;
        
        return [ NSString stringWithFormat:@"%@ %@",[self getWeek:[componets weekday]-1],[ChatTimeUtil stringFromDate:d format:@"HH:mm"]] ;
    }else{
        return [ChatTimeUtil stringFromDate:d format:@"yyyy-MM-dd HH:mm:ss"];
    }
    
}

//判断是否今天
+ ( BOOL )isToday:(NSDate *)d
{
    NSCalendar *calendar = [ NSCalendar currentCalendar ];
    int unit = NSCalendarUnitDay | NSCalendarUnitMonth |  NSCalendarUnitYear ;
    NSDateComponents *nowCmps = [calendar components :unit fromDate :[ NSDate date ]];
    NSDateComponents *selfCmps = [calendar components :unit fromDate : d ];
    return (selfCmps. year == nowCmps. year ) &&  (selfCmps. month == nowCmps. month ) && (selfCmps. day == nowCmps. day );
}

+(NSString *)getWeek:(NSInteger)week{
    switch (week) {
        case 1:
            return @"星期一";
            break;
        case 2:
            return @"星期二";
            break;
        case 3:
            return @"星期三";
            break;
        case 4:
            return @"星期四";
            break;
        case 5:
            return @"星期五";
            break;
        case 6:
            return @"星期六";
            break;
        default:
            return @"星期日";
            break;
    }
    
}
@end

转载于:https://my.oschina.net/u/564793/blog/360326