import UIKit

let dt = Date()

let currentCalendar = Calendar.current

1 let dateComp =currrentCalendar.dateComponens([Calendar.Component.era,
2                                               Calendar.Component.year,
3                                               Calendar.Component.month,
4                                               Calendar.Component.day,
5                                               Calendar.Component.year,
6                                               Calendar.Component.hour,
7                                               Calendar.Component.minute,
8                                               Calendar.Component.second],from dt)

1 dateComp.era
2 dateComp.year
3 dateComp.month
4 dateComp.day

1 dateComp.hour
2 dateComp.minute
3 dateComp.second

var comp = DateComponents()

1 comp.year = 2018
2 comp.month = 10
3 comp.day = 10

let compents = currentCalendar.date(from: comp)