iOS Swift 3 - UIDatePicker

In Swift 3 you can use DateComponents for that like this way.

First add action on datepicker for .valueChanged events.

datepicker.addTarget(self, action: #selector(dateChanged(_:)), for: .valueChanged)

Then get selected day, month and year using DateComponents in the action.

func dateChanged(_ sender: UIDatePicker) {
    let components = Calendar.current.dateComponents([.year, .month, .day], from: sender.date)
    if let day = components.day, let month = components.month, let year = components.year {
        print("\(day) \(month) \(year)")
    }
}

UIDatePicker in Swift 3 and Swift 4 example.

In Swift 3 You can use

1. Create Simple Project of Single View Application in swift 3
2. Drag a text field & connect to viewController
3. Date picker look like image

1. ViewController code is bellow..

     class ViewController: UIViewController {
        //Text Field Connection
      @IBOutlet weak var txtDatePicker: UITextField!
      //Uidate picker
      let datePicker = UIDatePicker()
   
       override func viewDidLoad() {
       super.viewDidLoad()
      //show date picker
        showDatePicker()
     }
   
   
      func showDatePicker(){
      //Formate Date
       datePicker.datePickerMode = .date
   
       //ToolBar
      let toolbar = UIToolbar();
      toolbar.sizeToFit()
   
      //done button & cancel button
       let doneButton = UIBarButtonItem(title: "Done", style: UIBarButtonItemStyle.bordered, target: self, action: "donedatePicker")
       let spaceButton = UIBarButtonItem(barButtonSystemItem: UIBarButtonSystemItem.flexibleSpace, target: nil, action: nil)
      let cancelButton = UIBarButtonItem(title: "Cancel", style: UIBarButtonItemStyle.bordered, target: self, action: "cancelDatePicker")
      toolbar.setItems([doneButton,spaceButton,cancelButton], animated: false)
   
   // add toolbar to textField
   txtDatePicker.inputAccessoryView = toolbar
    // add datepicker to textField
   txtDatePicker.inputView = datePicker
   
      }
   
    func donedatePicker(){
     //For date formate
      let formatter = DateFormatter()
      formatter.dateFormat = "dd/MM/yyyy"
      txtDatePicker.text = formatter.string(from: datePicker.date)
      //dismiss date picker dialog
      self.view.endEditing(true)
       }
   
         func cancelDatePicker(){
          //cancel button dismiss datepicker dialog
           self.view.endEditing(true)
         }
      }
   

2. Full Source project is given to github. github Link:https://github.com/enamul95/DatePicker1

   In Swift 4 or 5 you can use bellow code

    class ViewController: UIViewController {
   
      @IBOutlet weak var txtDatePicker: UITextField!
     let datePicker = UIDatePicker()
   
     override func viewDidLoad() {
       super.viewDidLoad()
        showDatePicker()
     }
   
   
     func showDatePicker(){
       //Formate Date
       datePicker.datePickerMode = .date
   
      //ToolBar
      let toolbar = UIToolbar();
      toolbar.sizeToFit()
      let doneButton = UIBarButtonItem(title: "Done", style: .plain, target: self, action: #selector(donedatePicker));
      let spaceButton = UIBarButtonItem(barButtonSystemItem: UIBarButtonSystemItem.flexibleSpace, target: nil, action: nil)
     let cancelButton = UIBarButtonItem(title: "Cancel", style: .plain, target: self, action: #selector(cancelDatePicker));
   
    toolbar.setItems([doneButton,spaceButton,cancelButton], animated: false)
   
     txtDatePicker.inputAccessoryView = toolbar
     txtDatePicker.inputView = datePicker
   
    }
   
     @objc func donedatePicker(){
   
      let formatter = DateFormatter()
      formatter.dateFormat = "dd/MM/yyyy"
      txtDatePicker.text = formatter.string(from: datePicker.date)
      self.view.endEditing(true)
    }
   
    @objc func cancelDatePicker(){
       self.view.endEditing(true)
     }
   }