CODEWITHSUNDEEP
swiftcalendarnsdatecomponents
PaFi
PaFi

Reputation: 920

Creating a date with DateComponents

I want to get the first day and the last day of the week. But my results do not match the documentation from apple: https://developer.apple.com/documentation/foundation/nsdatecomponents/1410442-weekday

This is my function:

func startAndEndDateOfWeek(weekOfYearWithYear: (week: Int,year: Int)) -> (start: Date, end: Date) {
    var output = (start: Date.init(), end: Date.init())

    let calendar = Calendar(identifier: .gregorian)
    var firstDayComponents = DateComponents()
    firstDayComponents.weekOfYear = weekOfYearWithYear.week
    firstDayComponents.yearForWeekOfYear = weekOfYearWithYear.year
    firstDayComponents.weekday = 1

    let firstDay = calendar.date(from: firstDayComponents)

    var lastDayComponents = DateComponents()
    lastDayComponents.weekOfYear = weekOfYearWithYear.week
    lastDayComponents.yearForWeekOfYear = weekOfYearWithYear.year
    lastDayComponents.weekday = 2

    let lastDay = calendar.date(from: lastDayComponents)
    output = (start: firstDay!, end: lastDay!)
    return output
}

.weekday = 2 -> leads to the sunday and not 0.

enter image description here

I also want to have the entire day and not 16:00.

Upvotes: 0

Views: 517

Answers (1)

Rob
Rob

Reputation: 437592

A couple of observations:

  1. In the Gregorian calendar, weekday = 1 means Sunday; weekday = 2 means Monday; etc. You can look at calendar.maximumRange(of: .weekday) to get the range of valid values, and you can look at calendar.weekdaySymbols to see what these weekDay values mean (e.g. “Sun”, “Mon”, “Tue”, “Wed”, “Thu”, “Fri”, and “Sat”).

  2. You said:

    I also want to have the entire day and not 16:00.

    A Date object references a moment in time. So it can’t represent an “entire day”. But it can represent midnight (and midnight in your time zone is likely 4pm in GMT/UTC/Zulu).

    You can, alternatively, return a DateInterval, which does represent a range of time.

    func interval(ofWeek week: Int, in year: Int) -> DateInterval {
    let calendar = Calendar.current

    let date = DateComponents(calendar: calendar, weekOfYear: week, yearForWeekOfYear: year).date!
    return calendar.dateInterval(of: .weekOfYear, for: date)!
}

    And then

    let formatter = DateIntervalFormatter()
formatter.dateStyle = .short
formatter.timeStyle = .short

let year = Calendar.current.component(.year, from: Date())
let dateInterval = interval(ofWeek: 2, in: year)
print(formatter.string(from: dateInterval))

    In a US locale, the interval starts on January 6th:

    1/6/19, 12:00 AM – 1/13/19, 12:00 AM

    Whereas in a German locale, the interval starts on the 7th:

    07.01.19, 00:00 – 14.01.19, 00:00

  3. If you want the start of the first day of the week and the last day of the week, you can do:

    func startAndEndDate(ofWeek week: Int, in year: Int) -> (Date, Date) {
    let date = DateComponents(calendar: calendar, weekOfYear: week, yearForWeekOfYear: year).date!
    let lastDate = calendar.date(byAdding: .day, value: 6, to: date)!

    return (date, lastDate)
}

    And then

    let formatter = DateFormatter()
formatter.dateStyle = .short

let year = Calendar.current.component(.year, from: Date())
let (start, end) = startAndEndDate(ofWeek: 2, in: year)
print(formatter.string(from: start), "-", formatter.string(from: end))

Upvotes: 2

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