cell业务逻辑处理(时间格式化)

 1  // 1.把帖子发布时间字符串转换成(NSDate)日期对象 => NSDateFormatter
 2     // NSDateFormatter:NSStreing与NSDate互转
 3     NSDateFormatter *fmt = [[NSDateFormatter alloc] init];
 4     // 设置格式
 5     fmt.dateFormat = @"yyyy-MM-dd HH:mm:ss";
 6     // 发布日期对象
 7     NSDate *createDate = [fmt dateFromString:item.create_time];
 8     
 9     // 获取日历类对象
10    // NSCalendar *calendar = [NSCalendar currentCalendar];
11     // 获取日期组件
12    // NSDateComponents *cmp = [calendar components:NSCalendarUnitHour | NSCalendarUnitMinute  fromDate:createDate toDate:[NSDate date] options:NSCalendarWrapComponents];
13   
14     NSString *timeStr = item.create_time;
15     if ([createDate isThisYear]) { 
16         if ([createDate isThisToday]) {
17            
18             // 获取日期差值
19             if (cmp.hour >= 1) {
20                 timeStr = [NSString stringWithFormat:@"%ld小时前",cmp.hour];
21             } else if (cmp.minute >= 2) {
22                 timeStr = [NSString stringWithFormat:@"%ld分钟前",cmp.minute];
23             } else { // 刚刚
24                 timeStr = @"刚刚";
25             }   
26         } else if ([createDate isThisYesterday]) { // 昨天
27             // 昨天 21:10
28             fmt.dateFormat = @"昨天 HH:mm";
29             timeStr = [fmt stringFromDate:createDate];
30    
31         } else { // 昨天之前 08-05 21:10:08
32             fmt.dateFormat = @"MM-dd HH:mm:ss";
33             timeStr = [fmt stringFromDate:createDate];
34         }
35     }
36  
37 因为判断日期要常用,我们就把判断方法抽取到NSDate的分类
38  
39 - (BOOL)isThisYear
40 {
41     // 获取当前日期对象
42     NSDate *curDate = [NSDate date]; 
43     // 获取日历类
44     NSCalendar *curCalendar = [NSCalendar currentCalendar];
45     // 获取自己日期组件(年,月,等)   self代码外面调用这个方法的日历类(也就是createDate)
46     NSDateComponents *selfCmp = [curCalendar components:NSCalendarUnitYear fromDate:self];
47     // 获取当前时间日期组件(年,月,等)
48     NSDateComponents *curCmp = [curCalendar components:NSCalendarUnitYear fromDate:curDate];
49     return  curCmp.year == selfCmp.year;
50 }
51 
52 // 判断是否是今天
53 - (BOOL)isThisToday
54 {
55     // 获取日历类
56     NSCalendar *curCalendar = [NSCalendar currentCalendar];
57     return [curCalendar isDateInToday:self];
58 }
59 
60 - (BOOL)isThisYesterday
61 {
62     NSCalendar *curCalendar = [NSCalendar currentCalendar];
63     return [curCalendar isDateInYesterday:self];
64 }