What is the correct date.format for MMM dd, yyyy h

问题:

I want convert this: Dec 31, 2017 8:00:00 PM to dd-mm-yyyy HH:ii format in Swift 4.

This is my code so far:

let dateFormatter = DateFormatter()
    dateFormatter.dateFormat = "MMM dd, yyyy hh:mm:ss a"//this your string date format

    if let translatedDate = dateFormatter.date(from: datetime) {
        dateFormatter.dateFormat = "dd-MM-yyyy HH:ii"
        return dateFormatter.string(from: translatedDate)
    }

The code never enters in the if statement. I guess my date format is not correct.

回答1:

A DateFormatter that converts between dates and their textual representations.

You can find more Locale identifier here.

• first, convert your date to local time zone. using a Locale class
• after you can covert the date in specific formate.

And try this code.

let dateStr = "Wed, 26 Jul 2017 18:10:02 +0530"
if let date = Date(fromString: dateStr, format: "MMM dd, yyyy hh:mm:ss a") {
        debugPrint(date.toString(format: "dd-MM-yyyy HH:ii"))
}

Date Extension is ...

extension Date {

    // Initializes Date from string and format
    public init?(fromString string: String, format: String, identifier: String = Locale.current.identifier) {
        let formatter = DateFormatter()
        formatter.dateFormat = format
        formatter.locale = Locale(identifier: identifier)
        if let date = formatter.date(from: string) {
            self = date
        } else {
            return nil
        }
    }

    // Converts Date to String, with format
    public func toString(format: String, identifier: String = Locale.current.identifier) -> String {
        let formatter = DateFormatter()
        formatter.locale = Locale(identifier: identifier)
        formatter.dateFormat = format
        return formatter.string(from: self)
    }
}

String Extension is ...

extension String {
    // Converts String to formated date string, with inputFormat and outputFormat
    public func toDate(form inputFormat: String, to outputFormat: String, identifier: String = Locale.current.identifier) -> String? {
        return Date(fromString: self, format: inputFormat, identifier: identifier)?.toString(format: outputFormat, identifier: identifier)
    }

    // Converts String to Date, with format
    func toDate(format: String, identifier: String = Locale.current.identifier) -> Date? {
        return Date(fromString: self, format: format, identifier: identifier)
    }
}