Code :
let dateString = \"2016-04-02\"
var formatter: NSDateFormatter = NSDateFormatter()
formatter.timeZone = NSTimeZone(abbreviati
let dateFormatter = DateFormatter()
//Your current Date Format
dateFormatter.dateFormat = "yyyy-MM-dd"
dateFormatter.locale = Locale(identifier: "en_US_POSIX")
dateFormatter.timeZone = TimeZone(secondsFromGMT: 0)
let finaldate = dateFormatter.date(from:"Your String")
//Your changing Date Format
dateFormatter.dateFormat = "MMM-dd"
let second = dateFormatter.string(from: finaldate!)