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Swift 使用NSDate获取星期几

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Swift 使用NSDate获取星期几,swift,nsdate,nscalendar,Swift,Nsdate,Nscalendar,我创建了一个方法，该方法应该以“YYYY-MM-DD”的形式接收字符串，并输出一个int，该int表示日期相对于所处周的位置（不管它是否在月份之间重叠）。例如，星期天=1，星期一=2，依此类推 这是我的密码： func getDayOfWeek(today:String)->Int{ var formatter:NSDateFormatter = NSDateFormatter() formatter.dateFormat = "YYYY-MM-DD" v

我创建了一个方法，该方法应该以“YYYY-MM-DD”的形式接收字符串，并输出一个int，该int表示日期相对于所处周的位置（不管它是否在月份之间重叠）。例如，星期天=1，星期一=2，依此类推

这是我的密码：

    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，但我已经尝试过大多数逻辑组合。而且还乱搞了
myComponents.weekdayOrdinal
，例如使用了
myComponents.day
或
.weekday

以下是我的使用选项：

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（或类似选项）。

您要找的（如果我理解正确的话）是
NSCalendarUnit.CalendarUnitWeekday
。
NSDateComponents
的相应属性是
weekday

还请注意，您的日期格式错误（ 完整规范可在此处找到：）

使用自动类型推断，函数可以稍微简化，并且在常量足够的情况下，可以大量使用变量。 此外，函数应返回一个可选值，即
nil
对于无效的输入字符串

更新了Swift 3及更高版本的代码：

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
}

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
    }
}
例如：

Swift 2的原始答案：

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
}

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
    }
}
用于Swift4从字符串获取工作日

   func getDayOfWeek(today:String)->Int {
        let formatter  = DateFormatter()
        formatter.dateFormat = "yyyy-MM-dd"
        let todayDate = formatter.date(from: today)!
        let myCalendar = NSCalendar(calendarIdentifier: NSCalendar.Identifier.gregorian)!
        let myComponents = myCalendar.components(NSCalendar.Unit.weekday, from: todayDate)
        let weekDay = myComponents.weekday
        return weekDay!
    }

let weekday = getDayOfWeek(today: "2018-10-10")
print(weekday) // 4
你可以用这张桌子 用于将日期转换为不同格式。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
就我而言，我每天都在寻找一个三个字母的字符串。我将@Martin R的函数修改如下：

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
    }
}
最后，我需要从日期开始添加一些字符串，包括一周的日期（例如“5”）和一年中的月份（例如8月）。下面是我根据@Martin R的函数创建并修改为返回3个字符字符串的所有三个函数：

//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
    }
}
斯威夫特3号和4号 在Swift 3中检索一周中的日期大大简化，因为
DateComponents
不再是可选的。这是一个扩展：

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
如果您正在查找星期一的书面本地化版本：

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
有一个更简单的方法。只需将字符串日期传递给以下函数，它将为您提供日期名称：）

SWIFT 2.0代码，表示从周一开始的当前周

@iAction func show（发件人：任意对象）{

//获取与日期格式相对应的周天数
让calendar=NSCalendar.currentCalendar（）
让dayInt:Int！
变量weekDate:[字符串]=[]
变量i=2
打印（“与日期对应的日期为”）
而（（dayInt-dayInt）+i<9）
{
让weekFirstDate=calendar.dateByAddingUnit（.Day，值：（-dayInt+i），toDate:NSDate（），选项：[]）
让dateFormatter=NSDateFormatter（）
dateFormatter.dateFormat=“EEEE dd MMMM”
让dayOfWeekString=dateFormatter.stringFromDate（weekFirstDate！）
追加（dayOfWeekString）
我++
}
因为我在工作日
{
print（i）//打印数组中存储的日期
}
}
//函数获取星期日
func getDayOfWeek（今天：字符串）->Int{
let formatter=NSDateFormatter（）
formatter.dateFormat=“MM dd yyyy”
让todayDate=formatter.dateFromString（今天）！
让myCalendar=NSCalendar（calendarIdentifier:nsCalendarIdentifierRegorian）！
让myComponents=myCalendar.components（.Weekday，fromDate:todayDate）
让weekDay=myComponents.weekDay
平日返回
}
@iAction func DateTitle（发件人：AnyObject）{
//获取与之对应的currentDate和weekDay
让currentDate=NSDate（）
让dateFormatter=NSDateFormatter（）
dateFormatter.dateFormat=“MM dd yyyy”
让dayOfWeekStrings=dateFormatter.stringFromDate（currentDate）
dayInt=getDayOfWeek（dayOfWeekStrings）
}
此代码用于查找当前整周。它是用Swift 2.0编写的：

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
}

var i=2
var weekday:[字符串]=[]
变量weekdate:[字符串]=[]
var weekmonth:[字符串]=[]
@iAction func按钮操作（发件人：AnyObject）{
让currentDate=NSDate（）
让dateFormatter=NSDateFormatter（）
dateFormatter.dateFormat=“MM dd yyyy”
让dayOfWeekStrings=dateFormatter.stringFromDate（currentDate）
让weekdays=getDayOfWeek（dayOfWeekStrings）
让calendar=NSCalendar.currentCalendar（）
而（（工作日-工作日）+i<9）
{
让weekFirstDate=calendar.dateByAddingUnit（.Day，值：（-weekdays+i），toDate:NSDate（），选项：[]）
let dayFormatter=NSDateFormatter（）
dayFormatter.dateFormat=“EEEE”
让dayOfWeekString=dayFormatter.stringFromDate（weekFirstDate！）
附加（dayOfWeekString）
让dateFormatter=NSDateFormatter（）
dateFormatter.dateFormat=“dd”
让dateOfWeekString=dateFormatter.stringFromDate（weekFirstDate！）
追加（dateOfWeekString）
让monthFormatter=NSDateFormatter（）
monthFormatter.dateFormat=“MMMM”
让monthOfWeekString=monthFormatter.stringFromDate（weekFirstDate！）
周月追加（月周字符串）
我++
}
对于（var j=0；jInt{
let formatter=NSDateFormatter（）
formatter.dateFormat=“MM dd yyyy”
让todayDate=formatter.dateFromString（今天）！
让myCalendar=NSCalendar（calendarIdentifier:nsCalendarIdentifierRegorian）！
让myComponents=myCalendar.components（.Weekday，fromDate:todayDate）
let daynumber=myComponents.weekday
返回日数
}
输出如下：

3月14日（星期一） 三月十五日（星期二） 三月十六日（星期三） 3月17日（星期四） 3月18日（星期五） 3月19日（星期六） 20三月（星期日）

如果您想要完整的“星期日”、“星期一”、“星期二”、“星期三”等

编辑：实际上有一种内置格式可以返回本地化的日期名称：

extension NSDate {
    func dayOfTheWeek() -> String? {        
        let dateFormatter = NSDateFormatter()
        dateFormatter.dateFormat = "EEEE"
        return dateFormatter.stringFromDate(self)
    }
}
我以前的解决方案（仅适用于英语）：

您不需要展开日历和组件，t 
extension NSDate {
    func dayOfTheWeek() -> String? {        
        let dateFormatter = NSDateFormatter()
        dateFormatter.dateFormat = "EEEE"
        return dateFormatter.stringFromDate(self)
    }
}

extension NSDate {

    func dayOfTheWeek() -> String? {
        let weekdays = [
            "Sunday",
            "Monday",
            "Tuesday",
            "Wednesday",
            "Thursday",
            "Friday",
            "Saturday"
        ]

        let calendar: NSCalendar = NSCalendar.currentCalendar()
        let components: NSDateComponents = calendar.components(.Weekday, fromDate: self)
        return weekdays[components.weekday - 1]
    }
}

print(myDate.dayOfTheWeek())

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
    }
}

Calendar.current.component(.weekday, from: Date())

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 DatewithMonth: String {
    let formatter = DateFormatter(); formatter.dateStyle = .medium ;        return formatter.string(from: self as Date)
}
}

extension Date {
    var weekdayOrdinal: Int {
        return Calendar.current.component(.weekday, from: self)
    }
}

let trivialDayStringsORDINAL = ["", "SUN","MON","TUE","WED","THU","FRI","SAT"]
// note that zero is not used

let dow = Calendar.current.component(.weekday, from: someDate)
print( trivialDayStringsORDINAL[dow] )

extension Date {

    /// Returns the day of the week as a `String`, e.g. "Monday"
    var dayOfWeek: String {
        let calendar = Calendar.autoupdatingCurrent
        return calendar.weekdaySymbols[calendar.component(.weekday, from: self) - 1]
    }
}

extension DateFormatter {

    /// returns a `DateFormatter` with the format "yyyy-MM-dd".
    static var standardDate: DateFormatter {
        let formatter = DateFormatter()
        formatter.dateFormat = "yyyy-MM-dd"
        return formatter
    }
}

DateFormatter.standardDate.date(from: "2018-09-18")!.dayOfWeek

    extension Date {

        var dayofTheWeek: String {
             let dayNumber = Calendar.current.component(.weekday, from: self)
             // day number starts from 1 but array count from 0
             return daysOfTheWeek[dayNumber - 1]
        }

        private var daysOfTheWeek: [String] {
             return  ["Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"]
        }
     }

let MyFormatter = DateFormatter()
MyFormatter.dateFormat = "EE MMM dd"
print(MyFormatter.string(from: Date()))

func dayOfWeek(date: Date()) -> String? {
    let dateFormatter = DateFormatter()
    dateFormatter.dateFormat = "EEEE"
    return dateFormatter.string(from: date).capitalized 
}


print(Date().dayOfWeek()!) // Monday

func dayOfWeek(date: Date()) -> String? {
    let dateFormatter = DateFormatter()
    dateFormatter.dateFormat = "EEE"
    return dateFormatter.string(from: date).capitalized 
}


print(Date().dayOfWeek()!) // Mon