此框架提供Ease of use的包装和Nsdate的类别。这个框架设计的关键因素是使用Nsdate的简单直观。
大部分日期算术的最小单位精度是一秒。
使用比较运算符直观地比较日期
let d1 = //Some date
let d2 = //Some other date
if d1 == d2 {}
if d1 != d2 {}
if d1 <= d2 {}
if d1 >= d2 {}
if d1 < d2 {}
if d1 > d2 {}
您可以使用加号或减号来分别添加或减去时间间隔。结果是新的日期。
let d1 = //Some date
let oneHour = 60.0 * 60.0
let d2 = d1 + oneHour
let d3 = d1 + 20.0
let d4 = d1 - oneHour
let d5 = d1 - 115.5
您还可以使用+将NsdateComponents添加。同样，结果是新的日期。
let d1 = //Some date
let comps = //Some date components
let d2 = d1 + comps
通过设置组件中的负值，可以完成减去组件。
您还可以通过使用减号从其它日期中减去一个Nsdate。结果是NSDateComponent
let d1 = //Some date
let d2 = //Some other date
let diffComps = d1 - d2
在我看来，添加日期并没有太大意义。
在这个框架中，我创建了一个概念，可以将时间周期添加到或从Nsdate对象中减去。以下是这个框架中预定义的时间周期：
Second
Minute
Hour
Day
Week
Month
Year
您可以使用这些时间周期进行日期算术
let date = //Some date
let afterASecond = date + Second()
let after20Seconds = date + Second(20)
let befor15Seconds = date - Second(15)
let after2Hours = date + Hour(2)
let beforeADay = date - Day()
let after4Weeks = date + Week(4)
let before2Years = date - Year(2)
let before2Weeks3daysAnd5Hours = date - Week(2) - Day(3) - Hour(5)
计算基于系统的当前日历。
关于添加或减去月份和年份的注意：添加一个月将增加日期的月份部分一个，如果月份是十二月，它将增加年份一个并将月份设为一月。同样适用于年份。
let d1 = \\Feb 19 2015, 13:30:30
let d2 = \\Mar 21 2015, 13:30:30
let res1 = d1 + Month() \\Mar 19 2015, 13:30:30 (adding 28 days)
let res2 = d2 + Month() \\Apr 21 2015, 13:30:30 (adding 31 days)
您还可以为日期算术定义自己的自定义时间周期。例如，两周或45分钟的讲座持续时间等。
public class Lecture: TimePeriodBase {
let lectureMinutes = 45.0
public class override var INTERVAL: NSTimeInterval {
return Minute.INTERVAL * Lecture().lectureMinutes
}
public override var interval: NSTimeInterval {
return Lecture.INTERVAL * Double(count)
}
public override var component: NSDateComponents {
var component = NSDateComponents()
component.minute = Int(Double(count) * lectureMinutes)
return component
}
public override var negativeComponent: NSDateComponents {
var component = NSDateComponents()
component.minute = -Int(Double(count) * lectureMinutes)
return component
}
}
let numLecturesInFirtHalf = 4
let firstLectureStarts = \\Some time
let secondLectureStarts = firstLectureStarts + Lecture()
...
let lastLectureStarts = firstLectureStarts + Lecture(numLectureInFirstHalf)
您也可以创建涉及多个日期组件的复杂持续时间。
使用计算属性访问日期组件。这些基于系统的当前日历。
let date = \\Mar 21 2015, 13:30:49
let second = date.second \\ 49
let minute = date.minute \\ 30
let hour = date.hour \\ 13
let day = date.day \\ 21
let weekDay = date.weekDay \\ 7 Sat
let month = date.month \\ 3
let year = date.year \\ 2015
let weekOfMonth = date.weekOfMonth \\ 3 - 3rd week
以下是一些创建基本日期的实用方法。
//Suppose it is right now Mar 21 2015, 13:30:49
let now = NSDate.now() \\Mar 21 2015, 13:30:49
let today = NSDate.today() \\Mar 21 2015, 00:00:00 - Start of today
let yesterday = NSDate.yesterday() \\Mar 20 2015, 00:00:00 - Start of yesterday
let tomorrow = NSDate.tomorrow() \\Mar 22 2015, 00:00:00 - Start of tomorrow
let dby = NSDate.dayBeforeYesterday() \\Mar 19 2015, 00:00:00
let dat = NSDate.dayAfterTomorrow() \\Mar 23 2015, 00:00:00
let thisMinute = NSDate.thisMinute() \\Mar 21 2015, 13:30:00 - Start of this minute
let thisHour = NSDate.thisHour() \\Mar 21 2015, 13:00:00 - Start of this hour
let thisWeek = NSDate.thisWeek() \\Mar 15 2015, 00:00:00 - Start of this week
let thisMonth = NSDate.thisMonth() \\Mar 1 2015, 00:00:00 - Start of this month
let thisYear = NSDate.thisYear() \\Jan 1 2015, 00:00:00 - Start of this year
以下方法提供了指定日期的开始和结束时间。
let date = //Mar 21 2015, 13:30:49
let startOfMinute = date.startOfMinute() //Mar 21 2015, 13:30:00
let endOfMinute = date.endOfMinute() //Mar 21 2015, 13:30:59
let startOfHour = date.startOfHour() //Mar 21 2015, 13:00:00
let endOfHour = date.endOfHour() //Mar 21 2015, 13:59:59
let startOfDay = date.startOfDay() //Mar 21 2015, 00:00:00
let endOfDay = date.endOfDay() //Mar 21 2015, 23:59:59
let startOfWeek = date.startOfWeek() //Mar 15 2015, 00:00:00
let endOfWeek = date.endOfWeek() //Mar 21 2015, 23:59:59
let startOfMonth = date.startOfMonth() //Mar 01 2015, 00:00:00
let endOfMonth = date.endOfMonth() //Mar 31 2015, 23:59:59
let startOfYear = date.startOfYear() //Jan 01 2015, 00:00:00
let endOfYear = date.endOfYear() //Dec 31 2015, 23:59:59
以下方法提供了指定日期的下一个月和上一个月的日期。
let date = //Mar 21 2015, 13:30:49
let nextMinute = date.nextfMinute() //Mar 21 2015, 13:31:00
let previousMinute = date.previousMinute() //Mar 21 2015, 13:29:00
let nextHour = date.nextHour() //Mar 21 2015, 14:00:00
let previousHour = date.previousHour() //Mar 21 2015, 12:00:00
let nextDay = date.nextfDay() //Mar 22 2015, 00:00:00
let previousDay = date.previousDay() //Mar 20 2015, 00:00:00
let nextWeek = date.nextWeek() //Mar 22 2015, 00:00:00
let previousWeek = date.previousWeek() //Mar 08 2015, 00:00:00
let nextMonth = date.nextMonth() //Apr 01 2015, 00:00:00
let previousMonth = date.previousMonth() //Feb 01 2015, 00:00:00
let nextYear = date.nextYear() //Jan 01 2016, 00:00:00
let previousYear = date.previousYear() //Jan 01 2014, 00:00:00
所有与日期相关的计算都使用系统默认日历，即NSCalendar.currentCalendar()。如果您想使用其他日历，可以通过以下方式实现：
NSCalendar.defaultCalendar = Some new calendar instance here
现在项目已成为您工作空间的一部分。您需要在目标部分将其引用添加到主项目。
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