小编典典

使用NSDate获取星期几

swift

我创建了一个方法,该方法应该采用“ YYYY-MM-
DD”形式的字符串,并吐出一个int,该int表示相对于它所在的星期的日期位置(无论两个月之间是否重叠)。因此,例如,sunday = 1 monday =
2,依此类推。

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
}

我知道这NSCalendarUnit.WeekdayOrdinalCalendar是错误的,但是我尝试了大多数逻辑组合。并且也搞砸了myComponents.weekdayOrdinal二手mycomponents.day或二手.weekday

这是我使用方式的选择:

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)。


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2020-07-07

共1个答案

小编典典

您正在寻找的是(如果我对问题的理解正确的话)NSCalendarUnit.CalendarUnitWeekday。的对应属性NSDateComponentsweekday

另请注意,您的日期格式不正确(可以在此处找到完整的规范:http
:
//unicode.org/reports/tr35/tr35-6.html)。

使用自动类型推断可以稍微简化该函数,在常量足够的情况下,也可以大量使用变量。另外,该函数应返回nil 用于无效输入字符串的可选参数。

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
}

例:

if let weekday = getDayOfWeek("2014-08-27") {
    print(weekday)
} else {
    print("bad input")
}

Swift 2的 原始答案

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
    }
}
2020-07-07