使用NSDate获取星期几
我创build了一个方法，该方法应该以“YYYY-MM-DD”forms取出一个string，并且吐出一个int值来表示相对于它所处的星期的date位置（不pipe它是否与月份重叠）。 所以例如星期日= 1星期一= 2等等。
这是我的代码：
func getDayOfWeek(today:String)->Int{ var formatter:NSDateFormatter = NSDateFormatter() formatter.dateFormat = "YYYY-MM-DD" var todayDate:NSDate = formatter.dateFromString(today)! var myCalendar:NSCalendar = NSCalendar(calendarIdentifier: NSGregorianCalendar) var myComponents = myCalendar.components(NSCalendarUnit.WeekdayOrdinalCalendarUnit, fromDate: todayDate) var weekDay = myComponents.weekdayOrdinal return weekDay } 我知道NSCalendarUnit.WeekdayOrdinalCalendar是错误的，但我已经试过我认为最合乎逻辑的组合。 并且还会使用mycomponents.day或.weekday来mycomponents.day myComponents.weekdayOrdinal 。
以下是我的选项：
static var EraCalendarUnit: NSCalendarUnit { get } static var YearCalendarUnit: NSCalendarUnit { get } static var MonthCalendarUnit: NSCalendarUnit { get } static var DayCalendarUnit: NSCalendarUnit { get } static var HourCalendarUnit: NSCalendarUnit { get } static var MinuteCalendarUnit: NSCalendarUnit { get } static var SecondCalendarUnit: NSCalendarUnit { get } static var WeekCalendarUnit: NSCalendarUnit { get } static var WeekdayCalendarUnit: NSCalendarUnit { get } static var WeekdayOrdinalCalendarUnit: NSCalendarUnit { get } static var QuarterCalendarUnit: NSCalendarUnit { get } static var WeekOfMonthCalendarUnit: NSCalendarUnit { get } static var WeekOfYearCalendarUnit: NSCalendarUnit { get } static var YearForWeekOfYearCalendarUnit: NSCalendarUnit { get } static var CalendarCalendarUnit: NSCalendarUnit { get } static var TimeZoneCalendarUnit: NSCalendarUnit { get }
我不清楚，因为没有DayOfWeekUnit选项（或类似的东西）。
你在找什么（如果我正确理解这个问题）是NSCalendarUnit.CalendarUnitWeekday 。 NSDateComponents的相应属性是weekday NSDateComponents 。
还要注意你的date格式是错误的（完整的规范可以在这里find： http : //unicode.org/reports/tr35/tr35-6.html ）。
该函数可以使用自动types推理稍微简化，在常量足够的情况下也可以使用很多variables：
func getDayOfWeek(today:String)->Int { let formatter = NSDateFormatter() formatter.dateFormat = "yyyy-MM-dd" let todayDate = formatter.dateFromString(today)! let myCalendar = NSCalendar(calendarIdentifier: NSCalendarIdentifierGregorian)! let myComponents = myCalendar.components(.Weekday, fromDate: todayDate) let weekDay = myComponents.weekday return weekDay } let weekday = getDayOfWeek("2014-08-27") print(weekday) // 4 = Wednesday
如果inputstring无效，该函数将在运行时崩溃。 正如Mike S正确地指出的那样，返回一个可选的是Swift方法来处理这种情况：
func getDayOfWeek(today:String)->Int? { let formatter = NSDateFormatter() formatter.dateFormat = "yyyy-MM-dd" if let todayDate = formatter.dateFromString(today) { let myCalendar = NSCalendar(calendarIdentifier: NSCalendarIdentifierGregorian)! let myComponents = myCalendar.components(.Weekday, fromDate: todayDate) let weekDay = myComponents.weekday return weekDay } else { return nil } }
这将用于：
if let weekday = getDayOfWeek("2014-08-27") { print(weekday) } else { print("bad input") }
（针对Swift 2 / Xcode 7更新）
Swift 3（Xcode 8）的更新：
func getDayOfWeek(_ today:String) -> Int? { let formatter = DateFormatter() formatter.dateFormat = "yyyy-MM-dd" guard let todayDate = formatter.date(from: today) else { return nil } let myCalendar = Calendar(identifier: .gregorian) let weekDay = myCalendar.component(.weekday, from: todayDate) return weekDay }
Swift 3＆4
由于DateComponents不再是可选的，所以在Swift 3中大大简化了检索星期几的DateComponents 。 这里是一个扩展：
extension Date { func dayNumberOfWeek() -> Int? { return Calendar.current.dateComponents([.weekday], from: self).weekday } } // returns an integer from 1 - 7, with 1 being Sunday and 7 being Saturday print(Date().dayNumberOfWeek()!) // 4
如果您正在寻找本周的书面本地化版本：
extension Date { func dayOfWeek() -> String? { let dateFormatter = DateFormatter() dateFormatter.dateFormat = "EEEE" return dateFormatter.string(from: self).capitalized // or use capitalized(with: locale) if you want } } print(Date().dayOfWeek()!) // Wednesday
如果你想要完整的“星期三”，“星期天”等
编辑：实际上有一个内置的格式，返回本地化的date名称：
extension NSDate { func dayOfTheWeek() -> String? { let dateFormatter = NSDateFormatter() dateFormatter.dateFormat = "EEEE" return dateFormatter.stringFromDate(self) } }
我以前的解决scheme（仅适用于英文）：
extension NSDate { func dayOfTheWeek() -> String? { let weekdays = [ "Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Satudrday," ] let calendar: NSCalendar = NSCalendar.currentCalendar() let components: NSDateComponents = calendar.components(.Weekday, fromDate: self) return weekdays[components.weekday - 1] } }
你不需要打开日历和组件，它们由基础框架保证。
用法：
print(myDate.dayOfTheWeek())
简单的答案（swift 3）：
Calendar.current.component(.weekday, from: Date())
在我的情况下，我是在每天三个字母的string之后。 我修改@Martin R的function如下：
func getDayOfWeekString(today:String)->String? { let formatter = NSDateFormatter() formatter.dateFormat = "yyyy-MM-dd" if let todayDate = formatter.dateFromString(today) { let myCalendar = NSCalendar(calendarIdentifier: NSCalendarIdentifierGregorian)! let myComponents = myCalendar.components(.Weekday, fromDate: todayDate) let weekDay = myComponents.weekday switch weekDay { case 1: return "Sun" case 2: return "Mon" case 3: return "Tue" case 4: return "Wed" case 5: return "Thu" case 6: return "Fri" case 7: return "Sat" default: print("Error fetching days") return "Day" } } else { return nil } }
有一个更简单的方法。 只要将你的stringdate传递给下面的函数，它会给你一天的名字:)
func getDayNameBy(stringDate: String) -> String { let df = NSDateFormatter() df.dateFormat = "YYYY-MM-dd" let date = df.dateFromString(stringDate)! df.dateFormat = "EEEE" return df.stringFromDate(date); }
Swift 3date延长
extension Date { var weekdayOrdinal: Int { return Calendar.current.component(.weekday, from: self) } }
您可以使用此表date_formats将您的date转换为不同的格式。 我的最短代码：
func getDayOfWeek(today: String) -> Int{ let formatter:NSDateFormatter = NSDateFormatter() formatter.dateFormat = "yyyy-MM-dd" let todayDate = formatter.dateFromString(today) formatter.dateFormat = "e" // "eeee" -> Friday let weekDay = formatter.stringFromDate(todayDate!) return Int(weekDay)! } getDayOfWeek("2015-12-18") // 6
实用的解决scheme…
请注意结果是从一到七的整数。
（不是零到六）
let trivialDayStringsORDINAL = ["", "SUN","MON","TUE","WED","THU","FRI","SAT"] // note that zero is not used
接着 …
let dow = Calendar.current.component(.weekday, from: someDate) print( trivialDayStringsORDINAL[dow] )
从date开始，我需要多一些string，包括一周的date（例如“5th”）和一年的月份（例如Aug）。 以下是我根据@Martin R的函数创build的所有三个函数，并修改为返回3个string：
//Date String Helper Functions func getDayOfWeek(today:String)->String? { let formatter = NSDateFormatter() formatter.dateFormat = "yyyy-MM-dd" if let todayDate = formatter.dateFromString(today) { let myCalendar = NSCalendar(calendarIdentifier: NSCalendarIdentifierGregorian)! let myComponents = myCalendar.components(.Weekday, fromDate: todayDate) let weekDay = myComponents.weekday switch weekDay { case 1: return "Sun" case 2: return "Mon" case 3: return "Tue" case 4: return "Wed" case 5: return "Thu" case 6: return "Fri" case 7: return "Sat" default: print("Error fetching days") return "Day" } } else { return nil } } func getDateOfMonth(today:String)->String? { let formatter = NSDateFormatter() formatter.dateFormat = "yyyy-MM-dd" if let todayDate = formatter.dateFromString(today) { let myCalendar = NSCalendar(calendarIdentifier: NSCalendarIdentifierGregorian)! let myComponents = myCalendar.components(.Day, fromDate: todayDate) let weekDay = myComponents.day switch weekDay { case 1: return "1st" case 2: return "2nd" case 3: return "3rd" case 4: return "4th" case 5: return "5th" case 6: return "6th" case 7: return "7th" case 8: return "8th" case 9: return "9th" case 10: return "10th" case 11: return "11th" case 12: return "12th" case 13: return "13th" case 14: return "14th" case 15: return "15th" case 16: return "16th" case 17: return "17th" case 18: return "18th" case 19: return "19th" case 20: return "20th" case 21: return "21st" case 22: return "22nd" case 23: return "23rd" case 24: return "24th" case 25: return "25th" case 26: return "26th" case 27: return "27th" case 28: return "28th" case 29: return "29th" case 30: return "30th" case 31: return "31st" default: print("Error fetching Date Of Month") return "Day" } } else { return nil } } func getMonthOfYear(today:String)->String? { let formatter = NSDateFormatter() formatter.dateFormat = "yyyy-MM-dd" if let todayDate = formatter.dateFromString(today) { let myCalendar = NSCalendar(calendarIdentifier: NSCalendarIdentifierGregorian)! let myComponents = myCalendar.components(.Month, fromDate: todayDate) let month = myComponents.month switch month { case 1: return "Jan" case 2: return "Feb" case 3: return "Mar" case 4: return "Apr" case 5: return "May" case 6: return "Jun" case 7: return "Jul" case 8: return "Aug" case 9: return "Sep" case 10: return "Oct" case 11: return "Nov" case 12: return "Dec" default: print("Error fetching months") return "Month" } } else { return nil } }
SWIFT 2.0代码提供从星期一开始的本周。
@IBAction func show（sender：AnyObject）{
// Getting Days of week corresponding to their dateFormat let calendar = NSCalendar.currentCalendar() let dayInt: Int! var weekDate: [String] = [] var i = 2 print("Dates corresponding to days are") while((dayInt - dayInt) + i < 9) { let weekFirstDate = calendar.dateByAddingUnit(.Day, value: (-dayInt+i), toDate: NSDate(), options: []) let dateFormatter = NSDateFormatter() dateFormatter.dateFormat = "EEEE dd MMMM" let dayOfWeekString = dateFormatter.stringFromDate(weekFirstDate!) weekDate.append(dayOfWeekString) i++ } for i in weekDate { print(i) //Printing the day stored in array } } // function to get week day func getDayOfWeek(today:String)->Int { let formatter = NSDateFormatter() formatter.dateFormat = "MMM-dd-yyyy" let todayDate = formatter.dateFromString(today)! let myCalendar = NSCalendar(calendarIdentifier: NSCalendarIdentifierGregorian)! let myComponents = myCalendar.components(.Weekday, fromDate: todayDate) let weekDay = myComponents.weekday return weekDay } @IBAction func DateTitle(sender: AnyObject) { // Getting currentDate and weekDay corresponding to it let currentDate = NSDate() let dateFormatter = NSDateFormatter() dateFormatter.dateFormat = "MMM-dd-yyyy" let dayOfWeekStrings = dateFormatter.stringFromDate(currentDate) dayInt = getDayOfWeek(dayOfWeekStrings) }
这个代码是查找整个当前周。 它是用Swift 2.0写的：
var i = 2 var weekday: [String] = [] var weekdate: [String] = [] var weekmonth: [String] = [] @IBAction func buttonaction(sender: AnyObject) { let currentDate = NSDate() let dateFormatter = NSDateFormatter() dateFormatter.dateFormat = "MMM-dd-yyyy" let dayOfWeekStrings = dateFormatter.stringFromDate(currentDate) let weekdays = getDayOfWeek(dayOfWeekStrings) let calendar = NSCalendar.currentCalendar() while((weekdays - weekdays) + i < 9) { let weekFirstDate = calendar.dateByAddingUnit(.Day, value: (-weekdays+i), toDate: NSDate(), options: []) let dayFormatter = NSDateFormatter() dayFormatter.dateFormat = "EEEE" let dayOfWeekString = dayFormatter.stringFromDate(weekFirstDate!) weekday.append(dayOfWeekString) let dateFormatter = NSDateFormatter() dateFormatter.dateFormat = "dd" let dateOfWeekString = dateFormatter.stringFromDate(weekFirstDate!) weekdate.append(dateOfWeekString) let monthFormatter = NSDateFormatter() monthFormatter.dateFormat = "MMMM" let monthOfWeekString = monthFormatter.stringFromDate(weekFirstDate!) weekmonth.append(monthOfWeekString) i++ } for(var j = 0; j<7 ; j++) { let day = weekday[j] let date = weekdate[j] let month = weekmonth[j] var wholeweek = date + "-" + month + "(" + day + ")" print(wholeweek) } } func getDayOfWeek(today:String)->Int { let formatter = NSDateFormatter() formatter.dateFormat = "MMM-dd-yyyy" let todayDate = formatter.dateFromString(today)! let myCalendar = NSCalendar(calendarIdentifier: NSCalendarIdentifierGregorian)! let myComponents = myCalendar.components(.Weekday, fromDate: todayDate) let daynumber = myComponents.weekday return daynumber }
输出将如下所示：
3月14日（星期一）15三月（星期二）16三月（星期三）17三月（星期四）18三月（星期五）19三月（星期六）20三月
func getDayOfWeek(today:String)->Int { let formatter = NSDateFormatter() formatter.dateFormat = "yyyy-MM-dd" let todayDate = formatter.dateFromString(today)! let myCalendar = NSCalendar(calendarIdentifier: NSCalendarIdentifierGregorian)! let myComponents = myCalendar.components(NSCalendarUnit.Weekday, fromDate: todayDate) let weekDay = myComponents.weekday return weekDay } let weekday = getDayOfWeek("2014-08-27") print(weekday) // 4
Swift 3：Xcode 8帮手function：
func getDayOfWeek(fromDate date: Date) -> String? { let cal = Calendar(identifier: .gregorian) let dayOfWeek = cal.component(.weekday, from: date) switch dayOfWeek { case 1: return "Sunday" case 2: return "Monday" case 3: return "Tuesday" case 4: return "Wednesday" case 5: return "Thursday" case 6: return "Friday" case 7: return "Saturday" default: return nil } }
extension Date { var weekdayName: String { let formatter = DateFormatter(); formatter.dateFormat = "E" return formatter.string(from: self as Date) } var weekdayNameFull: String { let formatter = DateFormatter(); formatter.dateFormat = "EEEE" return formatter.string(from: self as Date) } var monthName: String { let formatter = DateFormatter(); formatter.dateFormat = "MMM" return formatter.string(from: self as Date) } var OnlyYear: String { let formatter = DateFormatter(); formatter.dateFormat = "YYYY" return formatter.string(from: self as Date) } var period: String { let formatter = DateFormatter(); formatter.dateFormat = "a" return formatter.string(from: self as Date) } var timeOnly: String { let formatter = DateFormatter(); formatter.dateFormat = "hh : mm" return formatter.string(from: self as Date) } var timeWithPeriod: String { let formatter = DateFormatter(); formatter.dateFormat = "hh : mm a" return formatter.string(from: self as Date) } var dateOnly: String { let formatter = DateFormatter(); formatter.dateFormat = DATE_FORMAT return formatter.string(from: self as Date) } var fullDate: String { let formatter = DateFormatter(); formatter.dateFormat = DATE_FORMAT return formatter.string(from: self as Date) } var DatewithMonth: String { let formatter = DateFormatter(); formatter.dateStyle = .medium ; return formatter.string(from: self as Date) }
}
用法let weekday = Date（）。weekdayName
