iPhone - 我如何检查日期是否是星期一？

Question

我正在尝试查找日期是否为星期一。

为此，我这样做：

#define kDateAndHourUnitsComponents NSYearCalendarUnit | NSMonthCalendarUnit | NSDayCalendarUnit | NSHourCalendarUnit | NSMinuteCalendarUnit | NSSecondCalendarUnit
NSCalendar *calendar = [NSCalendar autoupdatingCurrentCalendar];

// for test and debug purpose
NSDateComponents* b = [calendar components:kDateAndHourUnitsComponents fromDate:retDate];
int a=[[calendar components:kDateAndHourUnitsComponents fromDate:theDate] weekday];
// -----------

if ([[calendar components:kDateAndHourUnitsComponents fromDate:theDate] weekday] == EKMonday) DoThis....

但这不起作用……a和b不包含任何有用的东西（a等于2147483647），

我也想知道 [calendar components:NSWeekdayCalendarUnit fromDate:retDate] 在这种情况下不再有用的用途......

我还发现这证实了这个过程： How to check what day of the week it is (i.e. Tues, Fri?) and compare two NSDates?

我错过了什么？

Answer 1

你去吧，这有效并通过整数返回天数：7 = Sat，1 = Sun，2 = Mon...

目标 C

NSDate* curDate = [NSDate date];
int dayInt = [[[NSCalendar currentCalendar] components: NSWeekdayCalendarUnit fromDate: curDate] weekday];

SWIFT 4.2

建立你想要检查星期几的日期

let dateComponents = DateComponents(
    year: 2019,
    month: 2 /*FEB*/,
    day: 23 /*23rd day of that month */
)

获取当前日历。

let cal = Calendar.current

现在使用日历检查构建日期是否为有效日期

guard let date = cal.date(from: dateComponents ) else {
    // The date you build up wasn't a valid day on the calendar
    return
}

//Now that your date is validated, get the day of the week

let weekdayIndex = cal.component(.weekday, from: date)

您会注意到“weekdayIndex”是一个整数。如果你想把它变成一个字符串，你可以这样做：

if let weekdayName = DateFormatter().weekdaySymbols?[ weekdayIndex - 1] {
    print("The weekday for your date is :: \(weekdayName)")
}

您当然可以使用let date = Date() 来获取当前星期几，而不是构建自己的日期