keyboardhide.swift

import UIKit

class ViewController: UIViewController, UITextFieldDelegate {

    @IBOutlet weak var txtInput: UITextField!
    
    @IBOutlet weak var txtOutput: UITextView!
    
    var items:[String] = []
    
    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
        
        self.txtInput.delegate = self
    }

    @IBAction func addItem(_ sender: Any) {
        if(txtInput.text! == ""){
            return
        }
        items.append(txtInput.text!)
        txtOutput.text = ""
        for item in items {
            txtOutput.text.append("\(item)\n")
        }
        txtInput.text = ""
        txtInput.resignFirstResponder()
    }
    
    func textFieldShouldReturn(_ textField: UITextField) -> Bool {
        if(txtInput.text! == ""){
            self.view.endEditing(false)
            return true
        }
        items.append(txtInput.text!)
        txtOutput.text = ""
        for item in items {
            txtOutput.text.append("\(item)\n")
        }
        txtInput.text = ""
        txtInput.resignFirstResponder()
        self.view.endEditing(true)
        return false
    }