Swift 간단한 계산기 앱 만들기 2(수정중)

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import UIKit

class ViewController: UIViewController {
    
    var displayNumber = ""
    var firstOperand = "" // 첫번째 피연산자
    var secondOperand = "" // 새로운 값 두번쨰 피연산자
    var result = ""       // 결과값
    var currentOperation: Operation = .Unkown // 연산자의 값을 저장하는 프로퍼티
    
    @IBOutlet weak var numberLabel: UILabel!
    

    @IBAction func numberBtn(_ sender: UIButton) {
        guard let numberValue = sender.title(for: .normal) else { return }
        if self.displayNumber.count < 9 {
            self.displayNumber += numberValue
            self.numberLabel.text = self.displayNumber
        }
    }
    
    @IBAction func clearBtn(_ sender: UIButton) { // 초기화(AC) 버튼
        self.displayNumber = ""
        self.firstOperand = ""
        self.secondOperand = ""
        self.result = ""
        self.currentOperation = .Unkown
        self.numberLabel.text = "0"
    }
    
    @IBAction func dotBtn(_ sender: UIButton) {
        if self.displayNumber.count < 8, !self.displayNumber.contains(".") {
            self.displayNumber += self.displayNumber.isEmpty ? "0." : "."
            self.numberLabel.text = self.displayNumber
        }
    }
    
    @IBAction func divideBtn(_ sender: UIButton) {
        self.operation(.Divide)
    }
    
    @IBAction func multiplyBtn(_ sender: UIButton) {
        self.operation(.Multiply)
    }
    
    @IBAction func minusBtn(_ sender: UIButton) {
        self.operation(.Minus)
    }
    @IBAction func plusBtn(_ sender: UIButton) {
        self.operation(.Plus)
    }
    
    @IBAction func equalBtn(_ sender: UIButton) {
        self.operation(self.currentOperation)
    }
    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view.
    }

    enum Operation {
        case Plus
        case Minus
        case Multiply
        case Divide
        case Unkown
    }
    
    func operation(_ operation: Operation) {
        if self.currentOperation != .Unkown {
            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 }
                
                switch self.currentOperation {
                case .Plus:
                    self.result = "\(firstOperand + secondOperand)"
                case .Minus:
                    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.numberLabel.text = self.result
            }
            
            self.currentOperation = operation
        } else {
            self.firstOperand = self.displayNumber
            self.currentOperation = operation
            self.displayNumber = ""
        }
    }
    
}

 

 

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