IOS中级篇 —— 日期时间对象

结合NSCalendar和NSDate能做更多的日期\时间处理 获得NSCalendar对象

NSCalendar *calendar = [NSCalendar currentCalendar];?获得年月日

- (NSDateComponents *)components:(NSCalendarUnit)unitFlags fromDate:(NSDate *)date;

//创建日期
NSDate?*d = [NSDate?date];

//创建日期对象
NSCalendar?*ca = [NSCalendar?currentCalendar];

//获得时间组件

NSDateComponents?*cms= [ca?components:NSCalendarUnitYear|NSCalendarUnitMonth|NSCalendarUnitDay fromDate:d];

NSLog(@"%ld-%ld-%ld",cms.year,cms.month,cms.day);

比较两个日期的差距
- (NSDateComponents *)components:(NSCalendarUnit)unitFlags fromDate:(NSDate *) startingDate toDate:(NSDate *)resultDate options:(NSCalendarOptions)opts;

NSString *time1 [email protected]"2014-04-08 20:50:40"; NSString *time2 [email protected]"2014-04-04 18:45:30";

NSDateFormatter *fmt = [[NSDateFormatter alloc] init]; fmt.dateFormat [email protected]"yyyy-MM-dd HH:mm:ss";

NSDate *date1 = [fmt dateFromString:time1]; NSDate *date2 = [fmt dateFromString:time2];

?//取时间较早的那个

? ?? [date2?earlierDate:date1];

? ? ? ?

?//取较晚的那个

? ?? [date2?laterDate:date1];

//把字符串转换成日期
? ? ? ? //和上边类似，仍然需要日期格式化对象，但是调用的方法从stringFromDate变成
? ? ? ? //因为时区设置的问题，这个日期被减去了一天
? ? ? ? NSDateFormatter?*format2=[[NSDateFormatter?alloc]init];
? ? ? ? [format2?setDateFormat:@"yyyy/MM/dd"];
? ? ? ? NSString?*[email protected]"2014/10/11";
? ? ? ? NSLog(@"%@",[format2?dateFromString:str2]);

// 1.创建一个日历对象
NSCalendar?*calendar = [NSCalendar?currentCalendar];

// 2.比较时间的差距
int?unit =?NSCalendarUnitYear?|?NSCalendarUnitMonth?|?NSCalendarUnitDay
|?NSCalendarUnitHour?|?NSCalendarUnitMinute?|?NSCalendarUnitSecond;?

NSDateComponents?*cmps = [calendar?components:unit?fromDate:date2?toDate:date1?options:0];

NSLog(@"相差%ld年%ld月%ld天%ld小时%ld分钟%ld秒", cmps.year, cmps.month, cmps.day, cmps.hour, cmps.minute, cmps.second);

计算日期

//1)明天的此刻

NSTimeInterval secondsPerDay = 24*60*60;
NSDate *tomorrow = [NSDate dateWithTimeIntervalSinceNow:secondsPerDay]; NSLog(@"myDate = %@",tomorrow);

//2)昨天的现在
NSTimeInterval secondsPerDay1 = 24*60*60;

NSDate *now = [NSDate date];

NSDate *yesterDay = [now addTimeInterval:-secondsPerDay1]; NSLog(@"yesterDay = %@",yesterDay);

格式化日期

NSDate ----> dateString

//定义NSDate
NSDate?*d1 = [NSDate?date];

//定义日期时间格式化的类
NSDateFormatter?*formatter = [[NSDateFormatter?alloc]?init]; [email protected]"yyyy-MM-dd HH:mm:ss";

//把Date转换为dataStr
NSString?*dateStr = [formatter?stringFromDate:d1];

• //??设置格式
• //??fmt.dateFormat = @"今天?HH:mm";
• //??HH : 24小时制
• //??hh : 12小时制
• //??yyyy :?年
• //??MM :?月
• //??dd :?号
• //??mm :?分钟
• //??ss :?秒
• //??Z :?时区