NSDate一年中的一天(swift) [英] NSDate day of the year (swift)
问题描述
如何用swift找到一年中的天数?有没有一种我没有看到的简单方法,或者我必须找到从1月1日到当前日期的秒数并除以一天中的秒数?
How might the day number of the year be found with swift? Is there a simple way that I'm not seeing, or do I have to find the number of seconds from Jan 1 to the current date and divide by the number of seconds in a day?
推荐答案
这是如何计算Objective-C中特定日期的一年中的某一天?到Swift。
Swift 2:
let date = NSDate() // now
let cal = NSCalendar.currentCalendar()
let day = cal.ordinalityOfUnit(.Day, inUnit: .Year, forDate: date)
print(day)
Swift 3:
let date = Date() // now
let cal = Calendar.current
let day = cal.ordinality(of: .day, in: .year, for: date)
print(day)
这为今年的第一天提供 1
,今天(2月) 56 = 31 + 25
25)。
This gives 1
for the first day in the year, and 56 = 31 + 25
for today (Feb 25).
...或者我必须找到1月的秒数1到当前日期
并除以一天中的秒数
... or do I have to find the number of seconds from Jan 1 to the current date and divide by the number of seconds in a day
这是一种错误的方法,因为一天没有固定的
秒数(从夏令时转换到夏令时)。
This would be a wrong approach, because a day does not have a fixed number of seconds (transition from or to Daylight Saving Time).
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