How to print name of the day of the week?

Question

Im trying to print out the name of the day of the week i.e Monday, Tuesday, Wednesday. I currently have this bit of code that does just that. I was wondering if there is a way to get rid of my switch statement and make this better. Thanks!

 func getDayOfWeek(_ today: String) -> String? {
    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)

    switch weekDay {
    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 ""
    }
}



getDayOfWeek("2018-3-5")

This prints out "Monday"

i'm not sure but maybe you should put 2018-03-05 instead? – koropok Mar 01 '18 at 03:51 — koropok, Mar 01 '18 at 03:51

Leo Dabus · Accepted Answer · 2019-11-20T18:25:23.967

5

You are using the wrong date format. The correct format is "yyyy-M-d". Besides that you can use Calendar property weekdaySymbols which returns the weekday localized.

func getDayOfWeek(_ date: String) -> String? {
    let formatter  = DateFormatter()
    formatter.dateFormat = "yyyy-M-d"
    formatter.locale = Locale(identifier: "en_US_POSIX")
    guard let todayDate = formatter.date(from: date) else { return nil }
    let weekday = Calendar(identifier: .gregorian).component(.weekday, from: todayDate)
    return Calendar.current.weekdaySymbols[weekday-1] // "Monday"
}

Another option is to use DateFormatter and set your dateFormat to "cccc" as you can see in this answer:

extension Formatter {
    static let weekdayName: DateFormatter = {
        let formatter = DateFormatter()
        formatter.dateFormat = "cccc"
        return formatter
    }()
    static let customDate: DateFormatter = {
        let formatter  = DateFormatter()
        formatter.dateFormat = "yyyy-M-d"
        formatter.locale = Locale(identifier: "en_US_POSIX")
        return formatter
    }()
}
extension Date {
    var weekdayName: String { Formatter.weekdayName.string(from: self) }
}

Using the extension above your function would look like this:

func getDayOfWeek(_ date: String) -> String? { Formatter.customDate.date(from: date)?.weekdayName }

Playground testing:

getDayOfWeek("2018-3-5")  // Monday
Date().weekdayName        // Thursday

edited Nov 20 '19 at 18:25

answered Mar 01 '18 at 03:52

Leo Dabus

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This actually is working! What If I don't want to use "locale"? Can I remove that line? – user7097242 Mar 01 '18 at 03:57
@user7097242 the locale is important if you are using a fixed date format. – Leo Dabus Mar 01 '18 at 03:58
Ok what is [weekday-1]? is that a hack or something? – user7097242 Mar 01 '18 at 03:58
weekdaySymbols returns an array. The first index is 0 so you need to subtract 1 – Leo Dabus Mar 01 '18 at 03:59
but that doesn't make to much sense since weekday returns value from 1-7 no? There is no 0? – user7097242 Mar 01 '18 at 04:07
the array contains 7 elements. The first is Sunday at index 0 and the last is Saturday at index 6. weekday returns 1 for Sunday and 7 for Saturday thats why you need to subtract 1 – Leo Dabus Mar 01 '18 at 04:10
For your second answer how can I do the same this as your first? Meaning how can I pass a string as a date instead of using a Date() object? – user7097242 Mar 01 '18 at 04:12
1

wow thats great stuff! It seems like its working on playgrounds. Thanks for the help. – user7097242 Mar 01 '18 at 04:16

score 1 · Answer 2 · answered Mar 26 '19 at 12:01

Use this function:

func DayOfWeek(date: String) -> String?
{
    let dateFormatter  = DateFormatter()
    dateFormatter.dateFormat = "yyyy-M-d"
    dateFormatter.locale = Locale(identifier: "en_US_POSIX")
    guard let _date = dateFormatter.date(from: date) else { return nil }
    let weekday = Calendar(identifier: .gregorian).component(.weekday, from: _date)
    return Calendar.current.weekdaySymbols[weekday-1]
}

How to print name of the day of the week?

2 Answers2

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