[swift] 직사각형 넓이 구하기

실행화면

ViewController.swift

//
//  ViewController.swift
//  BMICalc
//
//  Created by swuad_26 on 2022/01/03.
//

import UIKit

class ViewController: UIViewController {
    @IBOutlet weak var label1: UITextField!
    @IBOutlet weak var label2: UITextField!
    @IBOutlet weak var label3: UITextField!
    
    let numberFormatter:NumberFormatter = {
        let nf = NumberFormatter()
        nf.numberStyle = .decimal
        nf.minimumFractionDigits = 0
        nf.maximumFractionDigits = 2
        return nf
    }()
    
    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view.
    }

    @IBAction func doConvert(_ sender: UIButton) {
        if let value1 = label1.text, let num1 = Double(value1){
            if let value2 = label2.text, let num2 = Double(value2){
                let area = num1 * num2
                label3.text = numberFormatter.string(from: NSNumber(value: area))
                label1.resignFirstResponder()
                label2.resignFirstResponder()
            }
        }
    }
    @IBAction func dismissKeyboard(_ sender: Any) {
        label1.resignFirstResponder()
        label2.resignFirstResponder()
        label3.resignFirstResponder()
    }
}