今年：
今天：
刚刚， 小于一分钟
n分钟前， 大于一分钟，小于一小时
HH:mm:ss 大于一小时，今天之内
昨天：
昨天：HH：mm：ss 昨天
其他：
MM-dd HH:mm:ss 不是今天和昨天，但在今年内
非今年：
yyyy-MM-dd HH:mm:ss 不在今年
算法实现
扩展NSDate类：
@interface NSDate (PJXExtension)
-(NSDateComponents *)dateFrom:(NSDate *)from;
-(BOOL)isThisYear;
-(BOOL)isToday;
-(BOOL)isYesterday;
@end
#import "NSDate+PJXExtension.h"
@implementation NSDate (PJXExtension)
-(NSDateComponents *)dateFrom:(NSDate *)from
{
//日历对象
NSCalendar *calendar = [NSCalendar currentCalendar];
//比较时间
NSCalendarUnit unit = NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay|NSCalendarUnitHour|NSCalendarUnitMinute|NSCalendarUnitSecond;
NSDateComponents *cmps = [calendar components:unit fromDate:from toDate:self options:kNilOptions];
return cmps;
}
-(BOOL)isThisYear
{
NSCalendar *calendar = [NSCalendar currentCalendar];
NSInteger nowYear = [calendar component:NSCalendarUnitYear fromDate:[NSDate date]];
NSInteger selfYear =[calendar component:NSCalendarUnitYear fromDate:self];
return nowYear == selfYear;
}
-(BOOL)isToday
{
NSCalendar *calendar = [NSCalendar currentCalendar];
NSCalendarUnit unit = NSCalendarUnitYear | NSCalendarUnitMonth | NSCalendarUnitDay;
NSDateComponents *nowCmp = [calendar components:unit fromDate:[NSDate date]];
NSDateComponents *selfCmp = [calendar components:unit fromDate:self];
return nowCmp.year == selfCmp.year
&& nowCmp.month == selfCmp.month
&& nowCmp.day == selfCmp.day;
// //利用日历对象比较是否是今天
// NSDateFormatter *fmt = [[NSDateFormatter alloc]init];
// fmt.dateFormat = @"yyyy-MM-dd";
// NSString *nowStr = [fmt stringFromDate:[NSDate date]];
// NSString *selfStr = [fmt stringFromDate:self ];
// return [nowStr isEqualToString:selfStr];
}
-(BOOL)isYesterday
{
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 ]];
NSCalendar *calendar = [NSCalendar currentCalendar];
NSCalendarUnit unit = NSCalendarUnitYear|NSCalendarUnitMonth|NSCalendarUnitDay;
NSDateComponents *cmps = [calendar components:unit fromDate:selfDate toDate:nowDate options:kNilOptions];
return cmps.year==0
&& cmps.month == 0
&& cmps.day == 1;
}
@end
在显示类中实现
-(NSString *)setTime:(NSString *)time
{
NSLog(@"NSString time:%@",time);
//获得发帖的时间
NSDateFormatter *fmt = [[NSDateFormatter alloc]init];
fmt.dateFormat = @"yyyy-MM-dd HH:mm:ss";
NSDate *creat = [fmt dateFromString:time];
//显示时间的设置
NSString *text = nil;
if (creat.isThisYear) {
if(creat.isToday){
NSDateComponents *cmp = [[NSDate date] dateFrom:creat];
if (cmp.hour >= 1) {
text = [NSString stringWithFormat:@"%zd小时前",cmp.hour];
}else if(cmp.minute >= 1){
text = [NSString stringWithFormat:@"%zd分钟前",cmp.minute];
}else{
text = @"刚刚";
}
}else if(creat.isYesterday){
fmt.dateFormat = @"昨天: HH:mm:ss";
text = [fmt stringFromDate:creat];
}else{
fmt.dateFormat = @"MM-dd HH:mm:ss";
text = [fmt stringFromDate:creat];
}
}else{
text = time;
}
NSLog(@"Display time:%@",text);
return text;
}