Cómo crear una calculadora en Swift 5

Requisitos de hardware y sistema operativo

Opciones de entorno de desarrollo

• Xamarin . Las aplicaciones en esta plataforma están escritas usando C #. Con Xamarin, puede crear cualquier aplicación nativa de Android o aplicación IOS. El desarrollo se puede realizar con Visual Studio. A pesar de tales ventajas, lo más probable. algunos fragmentos de la aplicación deberán escribirse por separado para cada plataforma
• React Native. React , -. . , - , - . , .
• Flutter. , Flutter Dart Google. , , . , Flutter — React Native, . Dart, -
• PhoneGap/Cordova. Nitobi, Adobe. , PhoneGap, Apache Cordova, WebView,
• Unity. IOS, . , . gamedev.

Creando una calculadora

@IBOutlet var holder: UIView!

    var firstNumber = 0
    var resultNumber = 0
    var currentOperations: Operation?
        enum Operation {
        case add, subtract, multiply, divide
    }

    private var resultLabel: UILabel = {
        let label = UILabel()
        label.text = "0"
        label.textColor = .white
        label.textAlignment = .right
        label.font = UIFont(name: "Helvetica", size: 100)
        return label
    }()

    override func viewDidLayoutSubviews() {
        super.viewDidLayoutSubviews()

        setupNumberPad() //,      
    }

    private func setupNumberPad() {
        let FontSize:CGFloat = 25 
        //      
        let buttonSize: CGFloat = view.frame.size.width / 4 
        //    1/4
        let zeroButton = UIButton(frame: CGRect(x: 0, y: holder.frame.size.height-buttonSize, width: buttonSize*3, height: buttonSize))
        //  UIButton     
        zeroButton.setTitleColor(.black, for: .normal) 
        //    
        zeroButton.backgroundColor = .white
        //   
        zeroButton.setTitle("0", for: .normal) 
        //    0
        zeroButton.titleLabel?.font = UIFont(name: "Helvetica", size: FontSize)
        // , family    
        zeroButton.tag = 1 
        //         
        holder.addSubview(zeroButton)  //    holder 
        zeroButton.addTarget(self, action: #selector(zeroTapped), for: .touchUpInside) 
        //       
 

        for x in 0..<3 {
            let button_row_1 = UIButton(frame: CGRect(x: buttonSize * CGFloat(x), y: holder.frame.size.height-(buttonSize*2), width: buttonSize, height: buttonSize))
            //   x     x
            button_row_1.setTitleColor(.black, for: .normal) //
            button_row_1.backgroundColor = .white // 
            button_row_1.setTitle("\(x+1)", for: .normal) //  
            holder.addSubview(button_row_1) //    
            button_row_1.tag = x+2 // .. 1  ,   2
            button_row_1.addTarget(self, action: #selector(numberPressed(_:)), for: .touchUpInside)
            // 
        }

       for x in 0..<3 {
            let button_row_2 = UIButton(frame: CGRect(x: buttonSize * CGFloat(x), y: holder.frame.size.height-(buttonSize*3), width: buttonSize, height: buttonSize))
            button_row_2.setTitleColor(.black, for: .normal)
            button_row_2.backgroundColor = .white
            button_row_2.setTitle("\(x+4)", for: .normal)
            button_row_2.addSubview(button_row_2)
            button_row_2.tag = x+5
            button_row_2.addTarget(self, action: #selector(numberPressed(_:)), for: .touchUpInside)
        }
        
        for x in 0..<3 {
            let button_row_3 = UIButton(frame: CGRect(x: buttonSize * CGFloat(x), y: holder.frame.size.height-(buttonSize*4), width: buttonSize, height: buttonSize))
            button_row_3.setTitleColor(.black, for: .normal)
            button_row_3.backgroundColor = .white
            button_row_3.setTitle("\(x+7)", for: .normal)
            holder.addSubview(button_row_3)
            button_row_3.tag = x+8
            button_row_3.addTarget(self, action: #selector(numberPressed(_:)), for: .touchUpInside)
        }
    

        let clearButton = UIButton(frame: CGRect(x: 0, y: holder.frame.size.height-(buttonSize*5), width: view.frame.size.width - buttonSize, height: buttonSize))
        clearButton.setTitleColor(.black, for: .normal)
        clearButton.backgroundColor = .init(red: 0, green: 2, blue: 0.8, alpha: 1) //       rgb
         clearButton.titleLabel?.font = UIFont(name: "Helvetica", size: FontSize-4) //     
        clearButton.setTitle("CE", for: .normal)
        holder.addSubview(clearButton) //     holder
        clearButton.addTarget(self, action: #selector(clearResult), for: .touchUpInside) //  

        let operations = ["=","+", "-", "x", "÷"] //  

        for x in 0..<5 {
            let button_operand = UIButton(frame: CGRect(x: buttonSize * 3, y: holder.frame.size.height-(buttonSize * CGFloat(x+1)), width: buttonSize, height: buttonSize))
            button_operand.setTitleColor(.black, for: .normal)
            button_operand.backgroundColor = .init(red: 2, green: 0.8, blue: 0, alpha: 1) // 
            button_operand.setTitle(operations[x], for: .normal)
            holder.addSubview(button_operand)
            button_operand.tag = x+1 
            // ,       
            button_operand.titleLabel?.font = UIFont(name: "Helvetica", size: FontSize)
            button_operand.addTarget(self, action: #selector(operationPressed(_:)), for: .touchUpInside)
        }

    resultLabel.frame = CGRect(x: 20, y: clearButton.frame.origin.y - 110.0, width: view.frame.size.width - 40, height: 100)
    holder.addSubview(resultLabel)
} //    

Trabajando con manipuladores

    @objc func clearResult() {
        resultLabel.text = "0" //    0
        currentOperations = nil //    
        firstNumber = 0 //      0
    }
    
    @objc func zeroTapped() {
        //    
        if resultLabel.text != "0" {
            if let text = resultLabel.text {
                resultLabel.text = "\(text)\(0)" //  
            }
        }
    }

    @objc func numberPressed(_ sender: UIButton) {
        let tag = sender.tag - 1
        
        if resultLabel.text == "0" {
            resultLabel.text = "\(tag)"
        }
        else if let text = resultLabel.text {
        //   
            resultLabel.text = "\(text)\(tag)"
        }
    }

 @objc func operationPressed(_ sender: UIButton) {
        let tag = sender.tag
        
        if let text = resultLabel.text, let value = Int(text), firstNumber == 0 {
            //   
            firstNumber = value
            resultLabel.text = "0"
        }
        
        if tag == 1 {
            if let operation = currentOperations {
                var secondNumber = 0
                if let text = resultLabel.text, let value = Int(text) {
                    secondNumber = value
                }
                
                switch operation {
                case .add:
                    
                    firstNumber = firstNumber + secondNumber
                    secondNumber = 0 //  
                    resultLabel.text = "\(firstNumber)" 
                    currentOperations = nil
                    firstNumber = 0 //     Label 
                    
                    break
                    
                case .subtract:
                    firstNumber = firstNumber - secondNumber
                    secondNumber = 0
                    resultLabel.text = "\(firstNumber)"
                    currentOperations = nil
                    firstNumber = 0
                    
                    break
                    
                case .multiply:
                    firstNumber = firstNumber * secondNumber
                    secondNumber = 0
                    resultLabel.text = "\(firstNumber)"
                    currentOperations = nil
                    firstNumber = 0
                    
                    break
                    
                case .divide:
                    firstNumber = firstNumber / secondNumber
                    secondNumber = 0
                    resultLabel.text = "\(firstNumber)"
                    currentOperations = nil
                    firstNumber = 0
                    break
                }
            }
        }
        else if tag == 2 {
            currentOperations = .add 
            //     .    ,    
        }
        else if tag == 3 {
            currentOperations = .subtract
        }
        else if tag == 4 {
            currentOperations = .multiply
        }
        else if tag == 5 {
            currentOperations = .divide
        }
    }
}

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