you get the detail information from Apple Dateformatter Document.If you want to set the dateformat for your dateString, see this link , the detail dateformat you can get here
for e.g , do like
let formatter = DateFormatter()
// initially set the format based on your datepicker date / server String
formatter.dateFormat = "yyyy-MM-dd HH:mm:ss"
let myString = formatter.string(from: Date()) // string purpose I add here
// convert your string to date
let yourDate = formatter.date(from: myString)
//then again set the date format whhich type of output you need
formatter.dateFormat = "dd-MMM-yyyy"
// again convert your date to string
let myStringDate = formatter.string(from: yourDate!)
print(myStringDate)
you get the output as
