使用iPhone SDK的特定年份的天数？

Question

我想要获得当年的天数.

当我使用iPhone SDK尝试当月的天数解决方案时？,并通过NSYearCalendarUnit替换NSMonthCalendarUnit,我仍然获得该月的天数.

有谁知道我应该怎么做？

在此先感谢您的帮助.

Answer 1

这是NSCalendarSwift 2 中超精确的扩展:

extension NSCalendar {
    func daysInYear(date: NSDate = NSDate()) -> Int? {
        let year = components([NSCalendarUnit.Year], fromDate: date).year
        return daysInYear(year)
    }

    func daysInYear(year: Int) -> Int? {
        guard let begin = lastDayOfYear(year - 1), end = lastDayOfYear(year) else { return nil }
        return components([NSCalendarUnit.Day], fromDate: begin, toDate: end, options: []).day
    }

    func lastDayOfYear(year: Int) -> NSDate? {
        let components = NSDateComponents()
        components.year = year
        guard let years = dateFromComponents(components) else { return nil }

        components.month = rangeOfUnit(NSCalendarUnit.Month, inUnit: NSCalendarUnit.Year, forDate: years).length
        guard let months = dateFromComponents(components) else { return nil }

        components.day = rangeOfUnit(NSCalendarUnit.Day, inUnit: NSCalendarUnit.Month, forDate: months).length

        return dateFromComponents(components)
    }
}

你可以像这样使用它:

let calendar = NSCalendar.currentCalendar() // I'm using the Gregorian calendar
calendar.daysInYear()     // 365 (since it's currently 2015)
calendar.daysInYear(2016) // 366 (leap year!)

这是超级灵活的,因为我们不假设日历的长度:

let hebrew = NSCalendar(calendarIdentifier: NSCalendarIdentifierHebrew)
hebrew?.daysInYear(-7)   // 354
hebrew?.daysInYear(-100) // 384

请享用.

Answer 2

如果您只打算使用Gregorian Calender,您可以手动计算.

http://en.wikipedia.org/wiki/Leap_year#Algorithm

if year modulo 400 is 0 then leap
 else if year modulo 100 is 0 then no_leap
 else if year modulo 4 is 0 then leap
 else no_leap

Answer 3

我终于想出了一个有效的解决方案.我所做的是先计算一年中的月数,然后计算每个月的天数.

代码如下所示:

NSUInteger days = 0;
NSCalendar *calendar = [NSCalendar currentCalendar];
NSDate *today = [NSDate date];
NSDateComponents *components = [calendar components:NSYearCalendarUnit fromDate:today];
NSUInteger months = [calendar rangeOfUnit:NSMonthCalendarUnit
                                   inUnit:NSYearCalendarUnit
                                  forDate:today].length;
for (int i = 1; i <= months; i++) {
    components.month = i;
    NSDate *month = [calendar dateFromComponents:components];
    days += [calendar rangeOfUnit:NSDayCalendarUnit
                           inUnit:NSMonthCalendarUnit
                          forDate:month].length;
}

return days;

它并不像我希望的那样整洁,但它适用于任何日历,如普通的格里高利或伊斯兰日历.