NSDate为"下一小时的开始"

Question

我想倒计时到下一个小时.倒计时到特定时间非常容易,例如:

NSDate *midnight = [NSDate dateWithNaturalLanguageString:@"midnight tomorrow"]; 

如何为"每小时的开始"定义NSDate？

谢谢!

编辑:这是我目前的.无法将解决方案集成到我的代码中.任何帮助将不胜感激.:)

-(void)updateLabel {
NSDate *now = [NSDate date];

NSDate *midnight = [NSDate dateWithNaturalLanguageString:@"midnight tomorrow"]; 

//num of seconds between mid and now
NSTimeInterval timeInt = [midnight timeIntervalSinceDate:now];
int hour = (int) timeInt/3600;
int min = ((int) timeInt % 3600) / 60;
int sec = (int) timeInt % 60;
countdownLabel.text = [NSString stringWithFormat:@"%02d:%02d:%02d", hour, min,sec];
}  

Answer 1

正如+dateWithNaturalLanguageStringMacOS SDK上提供的那样,您的目标是iPhone,您需要制作自己的方法.我认为NSCalendar上课可以帮助你:

- (NSDate*) nextHourDate:(NSDate*)inDate{
    NSCalendar *calendar = [NSCalendar currentCalendar];
    NSDateComponents *comps = [calendar components: NSEraCalendarUnit|NSYearCalendarUnit| NSMonthCalendarUnit|NSDayCalendarUnit|NSHourCalendarUnit fromDate: inDate];
    [comps setHour: [comps hour]+1]; // Here you may also need to check if it's the last hour of the day
    return [calendar dateFromComponents:comps];
}

我没有检查过这段代码,但它(至少这种方法)必须有效.

Answer 2

最简单的方法可能是操纵时间戳,将其四舍五入到当前小时的开头并添加1小时

- (NSDate*)nextHourDateForDate:(NSDate*)date {
    NSTimeInterval timestamp = [date timeIntervalSince1970];
    NSTimeInterval current = timestamp - fmod(timestamp, 3600);
    NSTimeInterval next = current + 3600;

    return [NSDate dateWithTimeIntervalSince1970:next];
}

Answer 3

使用 DateComponents 和 Date，您可以通过向给定日期添加负数的分钟和一小时来获得它。

Swift3（作为扩展）：

extension Date {
    public var nextHour: Date {
        let calendar = Calendar.current
        let minutes = calendar.component(.minute, from: self)
        let components = DateComponents(hour: 1, minute: -minutes)
        return calendar.date(byAdding: components, to: self) ?? self
    }
}

使用它 let nextHourDate = myDate.nextHour

请参阅 Apple日期和时间编程指南以供参考。

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ObjectiveC（作为静态方法）：

+ (NSDate *)nextHourDate:(NSDate *)date{
    NSCalendar *calendar = [NSCalendar currentCalendar];
    NSDateComponents *components = [calendar components:NSMinuteCalendarUnit|NSHourCalendarUnit fromDate:date];
    components.minute = -components.minute;
    components.hour = 1;
    return [calendar dateByAddingComponents:components toDate:date options:0];
}

并调用它：

[YourClass nextHourDate:yourDate];