How to convert date format from dd/MM/YYYY to YYYY-MM-dd in swift [duplicate]

问题

I tired to covert from 21/07/2016 to 2016-07-21 but got this date 2015-12-20
Here is the Code that i have try

let inputFormatter = NSDateFormatter()
inputFormatter.dateFormat = "MM/dd/YYYY"

let outputFormatter = NSDateFormatter()
outputFormatter.dateFormat = "YYYY-MM-dd"

let showDate = inputFormatter.dateFromString("07/21/2016")
let resultString = outputFormatter.stringFromDate(showDate!)

print(resultString)

How to convert?
Thank you

回答1:

First changes your year formatter with yyyy and instead of using two NSDateFormatter use just one like this

let inputFormatter = NSDateFormatter()
inputFormatter.dateFormat = "MM/dd/yyyy"
let showDate = inputFormatter.dateFromString("07/21/2016")
inputFormatter.dateFormat = "yyyy-MM-dd"
let resultString = inputFormatter.stringFromDate(showDate!)
print(resultString)

For swift3

func convertDateFormater(_ date: String) -> String
    {
        let dateFormatter = DateFormatter()
        dateFormatter.dateFormat = "yyyy-MM-dd HH:mm:ss z"
        let date = dateFormatter.date(from: date)
        dateFormatter.dateFormat = "yyyy-MM-dd"
        return  dateFormatter.string(from: date!)

    }

回答2:

You can define a function like the one below:

// input string should always be in format "21/07/2016" ("dd/MM/yyyy")

func formattedDateFromString(dateString: String, withFormat format: String) -> String? {

    let inputFormatter = NSDateFormatter()
    inputFormatter.dateFormat = "dd/MM/yyyy"

    if let date = inputFormatter.dateFromString(dateString) {

      let outputFormatter = NSDateFormatter()
      outputFormatter.dateFormat = format

      return outputFormatter.stringFromDate(date)
    }

    return nil
}

You can use the above to pass an output format for your date string. Input format will always be dd/MM/yyyy. Then you use it as follows:

let stringA = formattedDateFromString("21/07/2016", withFormat: "yyyy-MM-dd")
let stringB = formattedDateFromString("21/07/2016", withFormat: "MMM dd, yyyy")

NSLog("stringA: \(stringA)") // 2016-07-21
NSLog("stringB: \(stringB)") // Jul 21, 2016

来源：https://stackoverflow.com/questions/38503489/how-to-convert-date-format-from-dd-mm-yyyy-to-yyyy-mm-dd-in-swift

标签

ios

swift

nsdateformatter