NSDate 整理笔记

1、 当前时间 

        NSDate *nowDate = [NSDate date]; 

        NSLog(@"nowDate = %@",nowDate); 

2、从现在开始的24小时 

        NSTimeInterval secondsPerDay = 24*60*60; 

        NSDate *tomorrow = [NSDate dateWithTimeIntervalSinceNow:secondsPerDay]; 

        NSLog(@"tomorrow = %@",tomorrow); 

3、根据已有日期创建日期 

         NSTimeInterval secondsPerDay1 = 24*60*60; 

        NSDate *now = [NSDate date]; 

        NSDate *yesterDay = [now addTimeInterval:-secondsPerDay1]; 

        NSLog(@"yesterDay = %@",yesterDay); 

4、比较日期 

        BOOL sameDate = [now isEqualToDate:yesterDay]; 

        NSLog(@"sameDate = %lu",sameDate); 

4.1、获取较早的日期 

        NSDate *earlierDate = [yesterDay earlierDate:now]; 

        NSLog(@"earlierDate  = %@",earlierDate); 

4.2、较晚的日期 

        NSDate *laterDate = [yesterDay laterDate:now]; 

        NSLog(@"laterDate  = %@",laterDate); 

 

4.3、两个日期之间相隔多少秒 

        NSTimeInterval secondsBetweenDates= [yesterDay timeIntervalSinceDate:now]; 

        NSLog(@"secondsBetweenDates=  %lf",secondsBetweenDates); 

4.4、通过NSCALENDAR类来创建日期 

        NSDateComponents *comp = [[NSDateComponents alloc]init]; 

        [comp setMonth:06]; 

        [comp setDay:01]; 

        [comp setYear:2001]; 

        NSCalendar *myCal = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar]; 

        NSDate *myDate1 = [myCal dateFromComponents:comp]; 

        NSLog(@"myDate1 = %@",myDate1); 

 

4.5、从已有日期获取日期 

        unsigned units  = NSMonthCalendarUnit|NSDayCalendarUnit|NSYearCalendarUnit; 

        NSDateComponents *comp1 = [myCal components:units fromDate:now]; 

        NSInteger month = [comp1 month]; 

        NSInteger year = [comp1 year]; 

        NSInteger day = [comp1 day]; 

4.6、NSDateFormatter实现日期的输出 

        NSDateFormatter *formatter = [[NSDateFormatteralloc]init]; 

        [formatter setDateStyle:NSDateFormatterFullStyle];//直接输出的话是机器码 

4.7、或者是手动设置样式[formatter setDateFormat:@"yyyy-mm-dd"]; 

        NSString *string = [formatter stringFromDate:now]; 
        NSLog(@"string = %@",string); 
        NSLog(@"formater = %@",formatter); 

4.8、获取日期格式对象

        - (NSDateFormatter *)dateFormatter { 

if (dateFormatter == nil) { 

dateFormatter = [[NSDateFormatter alloc] init]; 

[dateFormatter setDateStyle:NSDateFormatterMediumStyle]; 

[dateFormatter setTimeStyle:NSDateFormatterNoStyle]; 

} 

return dateFormatter; 

}

参考：http://www.cocoachina.com/bbs/read.php?tid=140980&keyword=NSDate