发帖时间分类

• 今年
  • 今天
    • 大于1小时 （xxx小时之前）
    • 小于1小时，大于1分钟 (xxx分钟之前)
    • 其它（1分钟内） （刚刚发布）
  • 昨天 （昨天 17:25）
  • 其它 (月-日 时:分:秒)
• 不是今年 （ (年-月-日 时:分:秒）

创建NSDate+LQLExtension

• NSDate+LQLExtension.h

  #import <Foundation/Foundation.h>
  @interface NSDate (LQLExtension)

//比较from与self的时间差值
- (NSDateComponents *)deltaFrom:(NSDate *)from;
/**
 *  是否为今年
 */
- (BOOL)isThisYear;
/**
 *  是否为今天
 */
- (BOOL)isToday;
/**
 *  是否为昨天
 */
- (BOOL)isYesterday;
@end

• NSDate+LQLExtension.m

#import "NSDate+LQLExtension.h"

@implementation NSDate (LQLExtension)

- (NSDateComponents *)deltaFrom:(NSDate *)from {
   
    //日历
    NSCalendar *calender = [NSCalendar currentCalendar];
    //比较时间
    NSCalendarUnit unit = NSCalendarUnitDay | NSCalendarUnitMonth | NSCalendarUnitYear |
    NSCalendarUnitHour | NSCalendarUnitMinute | NSCalendarUnitSecond;
    return [calender components:unit fromDate:from toDate:self options:0];
   




}

//[NSDate date] 当前时间

- (BOOL)isThisYear {
    
    //日历
    NSCalendar *calendar = [NSCalendar currentCalendar];
    
    NSInteger nowYear = [calendar component:NSCalendarUnitYear fromDate:[NSDate date]];
    NSInteger selfYear = [calendar component:NSCalendarUnitYear fromDate:self];
    
    return nowYear == selfYear;
    
}

- (BOOL)isToday {
    
    
    NSDateFormatter *fmt = [[NSDateFormatter alloc] init];
    fmt.dateFormat = @"yyyy-MM-dd";
    
    NSString *nowString = [fmt stringFromDate:[NSDate date]];
    NSString *selfString = [fmt stringFromDate:self];
    
    return [nowString isEqualToString:selfString];
}

- (BOOL)isYesterday {
    
    //日期格式化类
    NSDateFormatter *fmt = [[NSDateFormatter alloc] init];
    fmt.dateFormat = @"yyyy-MM-dd";
    
    NSDate *nowDate = [fmt dateFromString:[fmt stringFromDate:[NSDate date]]];
    NSDate *selfDate = [fmt dateFromString:[fmt stringFromDate:self]];
    
    //日历
    NSCalendar *calendar = [NSCalendar currentCalendar];
   
  //比较时间
    NSDateComponents *cmps = [calendar components:NSCalendarUnitDay | NSCalendarUnitMonth | NSCalendarUnitYear 
                            fromDate:selfDate toDate:nowDate options:0];
    
    return cmps.year == 0 && cmps.month == 0 && cmps.day == 1;
    
}

@end

帖子模型

• LQLTopic.h

/** 发帖时间*/
@property (nonatomic, copy) NSString *create_time;

• LQLTopic.m

- (NSString *)create_time {
    
    //日期格式化类
    NSDateFormatter *fmt = [[NSDateFormatter alloc] init];
    //设置日期格式：根据格式才可以解析
    fmt.dateFormat = @"yyyy-MM-dd HH:mm:ss";
    
    //帖子创建时间
    NSDate *create = [fmt dateFromString:_create_time];
    if (create.isThisYear) {//今年
        
        if (create.isToday) {//今天
            NSDateComponents *cmps = [[NSDate date]deltaFrom:create];
            if (cmps.hour >= 1) {//大于等于1小时
                return [NSString stringWithFormat:@"%zd小时前",cmps.hour];
            }else if (cmps.minute >= 1){//小于1小时，大于等于1分钟
                return [NSString stringWithFormat:@"%zd分钟前",cmps.minute];
            }else {//1分钟内
                return @"刚刚";
            }
            
        }else if (create.isYesterday){//昨天 
             fmt.dateFormat = @"昨天 HH:mm:ss";
            return [fmt stringFromDate:create];
            
        }else {//其它
            fmt.dateFormat = @"MM-dd HH:mm:ss";
            return [fmt stringFromDate:create];
        }
    }else{//不是今年   
        return _create_time;
    }    
}