Object-c 总结之NSDate

来源：互联网发布：linux守护线程编辑：程序博客网时间：2024/06/06 10:50

NSDate的常见用法总结

// 当前时间创建NSDate

NSDate *myDate = [NSDate date];

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

//从现在开始的24小时

NSTimeInterval secondsPerDay = 24*60*60;

NSDate *tomorrow = [NSDate dateWithTimeIntervalSinceNow:secondsPerDay];

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

//根据已有日期创建日期

NSTimeInterval secondsPerDay1 = 24*60*60;

NSDate *now = [NSDate date];

NSDate *yesterDay = [now addTimeInterval:-secondsPerDay1];(ios4之后被弃用了，在最后对新的方法作了补充)

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

//比较日期

BOOL sameDate = [now isEqualToDate:yesterDay];

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

//获取较早的日期

NSDate *earlierDate = [yesterDay earlierDate:now];

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

//较晚的日期

NSDate *laterDate = [yesterDay laterDate:now];

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

//两个日期之间相隔多少秒

NSTimeInterval secondsBetweenDates= [yesterDay timeIntervalSinceDate:now];

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

//通过NSCALENDAR类来创建日期

NSDateComponents *comp = [[NSDateComponentsalloc]init];

[comp setMonth:06];

[comp setDay:01];

[comp setYear:2001];

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

NSDate *myDate1 = [myCal dateFromComponents:comp];

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

//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];

//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

//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);

某一天的前一天或后一天的方法：

这里要用到的是NSCalendar，首先也是设置属性，和上面一样；用到最主要的方法是[comps setHour:+24]；+24表示获取下一天，-24表示获取前一天；还有[comps setMinute:0]和[comps setSecond:0]都要；

最后将calendar转换成NSdate；方法如下：

NSDate *nowDate = [calendar dateByAddingComponents:comps toDate:showDate options:0]; //showDate表示某天的date，nowDate表示showDate的前一天或下一天的date

代码如下：

    NSCalendar *calendar = [NSCalendar currentCalendar];
    NSDateComponents *comps;
    comps = [calendar components:(NSHourCalendarUnit | NSMinuteCalendarUnit | NSSecondCalendarUnit) fromDate:[[NSDate alloc] init]];

    [comps setHour:+24]; //+24表示获取下一天的date，-24表示获取前一天的date；
    [comps setMinute:0];
    [comps setSecond:0];
    NSDate *nowDate = [calendar dateByAddingComponents:comps toDate:showDate options:0];   //showDate表示某天的date，nowDate表示showDate的前一天或下一天的date

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