8

我想用我想要的小时：分钟：秒来设置 NSDate 时间，目前我正在使用 NSDate 组件，但它没有给出想要的结果

[comps setHour: -hours];
[comps setMinute:0];
[comps setSecond:0];
NSDate *minDate = [calendar_c dateFromComponents:comps];
4

6 回答 6

22

这作为一个NSDate类别非常有用。

/** Returns a new NSDate object with the time set to the indicated hour, 
  * minute, and second.
  * @param hour The hour to use in the new date.
  * @param minute The number of minutes to use in the new date.
  * @param second The number of seconds to use in the new date.
  */
-(NSDate *) dateWithHour:(NSInteger)hour 
                  minute:(NSInteger)minute 
                  second:(NSInteger)second 
{
   NSCalendar *calendar = [NSCalendar currentCalendar];
   NSDateComponents *components = [calendar components: NSYearCalendarUnit|
                                                         NSMonthCalendarUnit|
                                                         NSDayCalendarUnit
                                               fromDate:self];
    [components setHour:hour];
    [components setMinute:minute];
    [components setSecond:second];
    NSDate *newDate = [calendar dateFromComponents:components];
    return newDate;
}

对于上述类别，如果您有一个想要更改时间的现有日期，您可以这样做：

NSDate *newDate = [someDate dateWithHour:10 minute:30 second:00];

但是，如果您尝试从现有日期中增加或减少小时数，执行此操作的类别方法也很简单：

/** Returns a new date with the given number of hours added or subtracted.
  * @param hours The number of hours to add or subtract from the date.
  */
-(NSDate*)dateByAddingHours:(NSInteger)hours
{
    NSDateComponents *components = [[NSDateComponents alloc] init];
    [components setHour:hours];

    return [[NSCalendar currentCalendar] 
               dateByAddingComponents:components toDate:self options:0];
}
于 2013-08-14T19:00:56.253 回答
18

您的方法应该可以正常工作。我需要一个解决这种类型问题的方法（设置单独的日期组件），下面的代码按我的预期工作。我的情况：我想创建一个使用当前日期但将时间设置为作为字符串传入的值的日期对象。

NSString *string = @"7:00";
NSLocale *locale = [[NSLocale alloc] initWithLocaleIdentifier:@"en_US_POSIX"];
NSDateFormatter *timeOnlyFormatter = [[NSDateFormatter alloc] init];
[timeOnlyFormatter setLocale:locale];
[timeOnlyFormatter setDateFormat:@"h:mm"];

NSCalendar *calendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSGregorianCalendar];
NSDate *today = [NSDate date];
NSDateComponents *todayComps = [calendar components:(NSDayCalendarUnit | NSMonthCalendarUnit | NSYearCalendarUnit) fromDate:today];

NSDateComponents *comps = [calendar components:(NSHourCalendarUnit | NSMinuteCalendarUnit) fromDate:[timeOnlyFormatter dateFromString:string]];
comps.day = todayComps.day;
comps.month = todayComps.month;
comps.year = todayComps.year;
NSDate *date = [calendar dateFromComponents:comps];
[calendar release];
[timeOnlyFormatter release];
[locale release];

需要注意的一点是，在判断时间是否准确时，您确实必须注意时区。例如，在我的应用程序中，当您在断点处停止时，您会看到 GMT 时间（因此它看起来与输入时间不同，这是我的本地时间），但是当时间实际显示在屏幕上时应用程序，它正在被格式化以显示在本地时区。您可能需要考虑到这一点，以确定结果是否实际上与您的预期不同。

如果这没有帮助，您能否详细说明“没有给出预期的结果”？它给出了什么结果，与您的预期相比如何？

于 2011-09-25T16:24:26.287 回答
2

是 Swift2

extension NSDate {
    func dateWithHour (hour: Int, minute:Int, second:Int) ->NSDate?{

        let calendar = NSCalendar.currentCalendar(),
            components = calendar.components([.Day,.Month,.Year], fromDate: self)
        components.hour = hour;
        components.minute = minute;
        components.second = second;

        return calendar.dateFromComponents(components)
    }
}
于 2016-03-05T17:50:34.807 回答
1

您可以将 0 设置为小时、分钟和秒。

NSDateFormatter *tFmt = [[NSDateFormatter alloc] init];

tFmt.dateFormat = @"yyyy-MM-dd";

NSString *strNowDate = [NSString stringWithFormat:@"%@ 00:00:00",[tFmt stringFromDate:[NSDate date]]];

NSDate *nowDate = [NSDate dateWithString:strNowDate formatString:@"yyyy-MM-dd HH:mm:ss"];
于 2018-08-21T06:45:58.860 回答
1

Swift 5 解决方案（基于@dattk 答案），适用于那些担心弃用警告的人:)

func date(withHour hour: Int, withMinute minute: Int, withSeconds second: Int) -> Date? { 
   let now = Date() 
   let calendar = NSCalendar.current 
   var components = calendar.dateComponents([.day,.month,.year], from: now)   
   components.hour = hour 
   components.minute = minute 
   components.second = second 
   return calendar.date(from: components) 
}
于 2019-06-28T19:02:46.733 回答
0 
NSCalendar *calendar = [[NSCalendar alloc] initWithCalendarIdentifier:NSCalendarIdentifierGregorian];
NSDateComponents *comps = [calendar components:(NSCalendarUnitHour | NSCalendarUnitMinute) fromDate:[NSDate date]];
comps.hour = 0;
comps.minute = 15;
NSDate *date = [calendar dateFromComponents:comps];

iOS 8

于 2015-09-05T17:38:19.337 回答