is this code the best way to output this "2019/2/14 | 2019-2-14 | 2/14/2019" from input "2019/2/14"

func date_format2(date: String ) -> String {
  // write your code here
    let inputFormatter = DateFormatter()
       inputFormatter.dateFormat = "YYYY/m/d"
       let showDate = inputFormatter.date(from: date)
       let outputFormatter1 = DateFormatter()
        outputFormatter1.dateFormat = "YYYY/m/d" + " | " + "YYYY-m-d" + " | " + "m/d/YYYY"

       let resultString = outputFormatter1.string(from: showDate!)
        return resultString
}

This is how I would do it:

func date_format2(date: String ) -> String {
    let fmt = DateFormatter()
    fmt.dateFormat = "YYYY/m/d"
    guard let inputDate = fmt.date(from: date) else {
        return date
    }

    fmt.dateFormat = "YYYY/m/d" + " | " + "YYYY-m-d" + " | " + "m/d/YYYY"
    return fmt.string(from: inputDate)
}

Two notes:

• Reuses the DateFormatter object since those can be expensive to create. Just change the dateFormat property to the desired output format.
• Uses a guard to return an empty string if the input date cannot be converted to a Date rather than using a force unwrap.

Thank you, nice formatting.