How can I print a day of the week in a locale-friendly way using NSDateFormatter?

问题

I noticed NSDateFormatter allows for an enum called .FullStyle that will print Tuesday, April 12, 1952 AD.

But how do I just print Tuesday in a locale-safe way?

回答1:

You need to use NSDateFormatter dateFormat = "cccc". If you need a reference for date format patterns you can take a look at this link:

extension NSDate {
    struct Formatter {
        static let dayOfWeek: NSDateFormatter = {
            let formatter = NSDateFormatter()
            formatter.dateFormat = "cccc"   // Stand Alone local day of week
            return formatter
        }()
    }
    var dayOfWeek: String {
        return Formatter.dayOfWeek.stringFromDate(self)
    }
}

print(NSDate().dayOfWeek)   // Wednesday

---

Xcode 8 beta 3 • Swift 3

extension DateFormatter {
    convenience init(dateFormat: String) {
        self.init()
        self.dateFormat = dateFormat
    }
}

extension Date {
    struct Formatter {
        static let dayOfWeek = DateFormatter(dateFormat: "cccc")  // Stand Alone local day of week
    }
    var dayOfWeek: String {
        return Formatter.dayOfWeek.string(from: self)
    }
}

print(Date().dayOfWeek)   // Wednesday

回答2:

You can set formatter.dateFormat = "EEEE" as Leo Dabus suggests.

If you have the day of week, you can use it as an index into the formatter's weekdaySymbols. Example:

let formatter = NSDateFormatter()
let weekday = formatter.calendar.component(.Weekday, fromDate: NSDate())
let weekdaySymbol = formatter.weekdaySymbols[weekday]
// result: "Saturday" (for example)

来源：https://stackoverflow.com/questions/36511423/how-can-i-print-a-day-of-the-week-in-a-locale-friendly-way-using-nsdateformatter