How its work :
let date = NSDate()
let calender = NSCalendar(calendarIdentifier: NSCalendarIdentifierPersian)
let components = calender?.components(NSCalendarUnit(UInt.max), fromDate: date)
let year = components!.year
let month = components!.month
let day = components!.day
txtDate.text = "\(year)/\(month)/\(day)"