How to add localisation for date formatter in iOS-CodePudding

I am using the following function format the time in my project.

func formatTime() -> String {
        let dateFormatter = DateFormatter()
        let tempLocale = dateFormatter.locale
        dateFormatter.locale = Locale(identifier: "en_US")
        dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss.SSS'Z'"
        dateFormatter.timeZone = TimeZone.init(abbreviation: "UTC")
        dateFormatter.amSymbol = "AM"
        dateFormatter.pmSymbol = "PM"
        if let callTime = callTime {
            if let date = dateFormatter.date(from: callTime) {
                dateFormatter.timeZone = TimeZone.current
                dateFormatter.dateFormat = "MMMM dd yyyy hh:mm a"
                dateFormatter.locale = tempLocale
                let dateString = dateFormatter.string(from: date)
               return dateString
            } else {
                return ""
            }
        } else {
            return ""
        }
    }

For this function I am getting output

January 18 2023 04:36 PM

In my project I am English and Chinese language. After switching the language to Chinese the date string still remains same. I want to localise the month to Chinese. How to do that ?

CodePudding user response：

If you want to localize the date you need a template rather than a fixed date format.

This function takes a date string and a locale

func formatTime(callTime: String, locale: Locale?) -> String {
    let dateFormatter = DateFormatter()
    let tempLocale = locale ?? dateFormatter.locale
    dateFormatter.locale = Locale(identifier: "en_US")
    dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss.SSSZ" // no single quotes!
    if let date = dateFormatter.date(from: callTime) {
        dateFormatter.locale = tempLocale
        dateFormatter.setLocalizedDateFormatFromTemplate("MMMMddyyyyhhmm")
        return dateFormatter.string(from: date)
    } else {
        return ""
    }
}

or simpler rather than a template or fixed date format specify dateStyle and timeStyle

func formatTime(callTime: String, locale: Locale?) -> String {
    let dateFormatter = DateFormatter()
    let tempLocale = locale ?? dateFormatter.locale
    dateFormatter.timeZone = TimeZone.init(abbreviation: "UTC")
    dateFormatter.locale = Locale(identifier: "en_US")
    dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss.SSSZ"
    if let date = dateFormatter.date(from: callTime) {
        dateFormatter.locale = tempLocale
        dateFormatter.timeStyle = .short
        dateFormatter.dateStyle = .long
        return dateFormatter.string(from: date)
    } else {
        return ""
    }
}

Now call it with US and Chinese locale

let usDate = formatTime(callTime: "2022-01-18T13:12:00.111Z", locale: Locale(identifier: "en_US"))
print(usDate)      // January 18, 2022 at 1:12 PM

let chineseDate = formatTime(callTime: "2022-01-18T13:12:00.111Z", locale: Locale(identifier: "zh_TW"))
print(chineseDate) // 2022年1月18日 下午1:12