Swift 3 changing date format

问题

I want to get my Date in DD.MM.YYYY HH:mm:ss as a String.

I use the following extension:

extension Date {
var localTime: String {
    return description(with: Locale.current)
    }
}

and the following code when my datePicker changes:

@IBAction func datePickerChanged(_ sender: UIDatePicker) {
    dateLabel.text = datePicker.date.localTime
    let formatter = DateFormatter()
    formatter.dateFormat = "dd.MM.yyyy hh:mm"
    let TestDateTime = formatter.date(from: datePicker.date.localTime)
}

What am I doing wrong?

回答1:

Your code is completely wrong. Just do the following:

@IBAction func datePickerChanged(_ sender: UIDatePicker) {
    let formatter = DateFormatter()
    formatter.dateFormat = "dd.MM.yyyy HH:mm"

    dateLabel.text = formatter.string(from: sender.date)
}

This will convert the date picker's chosen date to a string in the format dd.MM.yyyy HH:mm in local time.

Never use the description method to convert any object to a user presented value.

回答2:

Just used the function in your code(swift 4.2).

public func convertDateFormatter(date: String) -> String {

let dateFormatter = DateFormatter()
dateFormatter.dateFormat = "yyyy-MM-dd'T'HH:mm:ss.SSS'Z'"//this your string date format
dateFormatter.timeZone = NSTimeZone(name: "UTC") as TimeZone!
dateFormatter.locale = Locale(identifier: "your_loc_id")
let convertedDate = dateFormatter.date(from: date)

guard dateFormatter.date(from: date) != nil else {
assert(false, "no date from string")
return ""
}
dateFormatter.dateFormat = "HH:mm a"///this is what you want to convert format
dateFormatter.timeZone = NSTimeZone(name: "UTC") as TimeZone!
let timeStamp = dateFormatter.string(from: convertedDate!)
print(timeStamp)
return timeStamp
}

Thanks

来源：https://stackoverflow.com/questions/41577781/swift-3-changing-date-format