계산기 앱

 

< 주요 기능 >

UIStackView 

IBInspecter, IBDesignable

 

 

- 계산 기능 구현

//
//  ViewController.swift
//  Calculator
//
//  Created by YANG on 2022/04/03.
//

import UIKit

enum Operation {
    case Add
    case Subtract
    case Divide
    case Multiply
    case Unknown
}

class ViewController: UIViewController {

    @IBOutlet weak var numberOuputLabel: UILabel!
    
    var displayNumber = "" // 계산기버튼을 누를때마다 numberOutputLabel에 표시되는 숫자
    var firstOperand = ""  // 이전 계산값을 저장
    var secondOperand = "" // 새롭게 입력되는 값을 저장
    var result = ""
    var currentOperation: Operation = .Unknown // 현재 계산기에 어떤 연산자가 입력되었는지. 연산자의 값을 저장
    
    
    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view.
    }

    
    @IBAction func tapNumberBtn(_ sender: UIButton) {
        guard let numberValue = sender.title(for: .normal) else { return }
        if self.displayNumber.count < 9 {
            self.displayNumber += numberValue
            self.numberOuputLabel.text = self.displayNumber
        }
        
    }
    
    @IBAction func tapClearBtn(_ sender: UIButton) {
        self.displayNumber = ""
        self.firstOperand = ""
        self.secondOperand = ""
        self.result = ""
        self.currentOperation = .Unknown
        self.numberOuputLabel.text = "0"
        
    }
    
    @IBAction func tapDotBtn(_ sender: UIButton) {
        if self.displayNumber.count < 8, !self.displayNumber.contains(".") {
            self.displayNumber += self.displayNumber.isEmpty ? "0." : "."
            self.numberOuputLabel.text = self.displayNumber
        }
    }
    
    @IBAction func tabDivideBtn(_ sender: UIButton) {
        self.operation(.Divide)
    }
    
    @IBAction func tabMultiplyBtn(_ sender: UIButton) {
        self.operation(.Multiply)
    }
    
    
    @IBAction func tabSubtractBtn(_ sender: UIButton) {
        self.operation(.Subtract)
    }

    @IBAction func tabAddBtn(_ sender: UIButton) {
        self.operation(.Add)
    }
    
    @IBAction func tabEqualBtn(_ sender: UIButton) {
        self.operation(self.currentOperation)
    }
    
    // 계산을 담당하는 함수
    func operation(_ operation: Operation) {
        if self.currentOperation != .Unknown {  // 연산자 버튼이 눌려있는 상태
            if !self.displayNumber.isEmpty {
                self.secondOperand = self.displayNumber
                self.displayNumber = ""
                
                guard let firstOperand = Double(self.firstOperand) else { return }
                guard let secondOperand = Double(self.secondOperand) else { return }
                
                // 연산 수행
                switch self.currentOperation {
                case .Add:
                    self.result = "\(firstOperand + secondOperand)"
                case .Subtract:
                    self.result = "\(firstOperand - secondOperand)"
                    
                case .Divide:
                    self.result = "\(firstOperand / secondOperand)"
                    
                case .Multiply:
                    self.result = "\(firstOperand * secondOperand)"
                    
                default:
                    break
                }
                
                if let result = Double(self.result), result.truncatingRemainder(dividingBy: 1) == 0 {
                    self.result = "\(Int(result))"
                }
            
                self.firstOperand = self.result
                self.displayNumber = self.result
            }
            
            self.currentOperation = operation
            
        } else {  // 연산자버튼이 안눌린 상태 -> 연산자 버튼 클릭
            self.firstOperand = self.displayNumber
            self.currentOperation = operation // 선택한 연산자
            self.displayNumber = ""
            
        }
        
    }
    
}