範例：簡單型計算機

Objective

此實作參考 [1]，而試著將 Objective-C 程式 Port 到 Swift 3.0 程式

Lab

1. 新增 Single View Application 專案
2. UI 設計

Code

1. File Calculation.swift

//

//  Calculation.swift

//  myCaculatorDemo

//

//  Created by Elvis Meng on 2017/5/4.

//  Copyright © 2017年 Elvis Meng. All rights reserved.

//

import Foundation

class Calculation : NSObject {

    var operandA : Float?

    var operandB : Float?

    var op : Character?

    var isFirstOperand : Bool

    var result : Float?

    

    override init() {

        operandA = 0.0

        operandB = 0.0

        op = nil

        isFirstOperand = true

        result = 0.0

    }

    

    func calculateResult(operandA : Float, operandB : Float, op : Character) -> Float {

        switch op {

        case "+" :

            result = operandA + operandB

        case "-" :

            result = operandA - operandB

        case "*" :

            result = operandA * operandB

        case "/" :

            result = operandA / operandB

        default :

            print("error")

        }

        return result!

    }

    

}

2. File : ViewController.swift

//

//  ViewController.swift

//  myCaculatorDemo

//

//  Created by Elvis Meng on 2017/4/25.

//  Copyright © 2017年 Elvis Meng. All rights reserved.

//

import UIKit

class ViewController: UIViewController {

    @IBOutlet weak var displayResult: UILabel!

    

    var cal:Calculation = Calculation()

    var isFirstDigit = true

    var hasTapEqual = false

    var operand:Float = 0.0

    var result:Float = 0.0

    var digitCount = 0

    var digit = 0

    

    func processCalc(op:Character){

        if (cal.isFirstOperand){

            cal.operandA = operand

            cal.isFirstOperand = false

        }

        else if (hasTapEqual){

            cal.operandA = result

            cal.operandB = operand

            hasTapEqual = false

        }

        else {

            cal.operandB = operand

            result = cal.calculateResult(operandA: cal.operandA!, operandB: cal.operandB!, op: op)

            displayProcess(num: result)

            cal.operandA = result

        }

        cal.op = op

        operand = 0.0

        digitCount = 0

    }

    

    @IBAction func tapDigit(_ sender: UIButton) {

        digit = sender.tag

        if hasTapEqual == true {

            displayResult.text = "0.0"

            cal.operandA = 0

            cal.operandB = 0

            cal.isFirstOperand = true

            result = 0

            operand = 0

            isFirstDigit = true

            hasTapEqual = false

        }

        if (isFirstDigit && digit == 0){

            isFirstDigit = true

        } else {

            if (digitCount >= 15) {

                return

            }

            isFirstDigit = false

            operand = operand * 10 + Float(digit)

            displayProcess(num: operand)

        }

        digitCount += 1

    }

    

    @IBAction func tapPlus(_ sender: UIButton) {

        processCalc(op: "+")

    }

    

    @IBAction func tapMinus(_ sender: UIButton) {

        processCalc(op: "-")

    }

    @IBAction func tapMultiply(_ sender: UIButton) {

        processCalc(op: "*")

    }

    

    @IBAction func tapDivide(_ sender: UIButton) {

        processCalc(op: "/")

    }

    

    

    @IBAction func tapEqual(_ sender: UIButton) {

        if (cal.isFirstOperand == false){

            cal.operandB = operand

            result = cal.calculateResult(operandA: cal.operandA!, operandB: cal.operandB!, op: cal.op!)

            self.displayProcess(num: result)

            cal.operandA = result

            hasTapEqual = true

        }

    }

    

    @IBAction func tapAC(_ sender: UIButton) {

        displayResult.text = "0.0"

        cal.operandA = 0

        cal.operandB = 0

        cal.isFirstOperand = true

        result = 0

        operand = 0

        isFirstDigit = true

        hasTapEqual = false

    }

    

    func displayProcess(num:Float){

        displayResult.text = String(num)

    }

    

    override func viewDidLoad() {

        super.viewDidLoad()

        // Do any additional setup after loading the view, typically from a nib.

        let cal:Calculation = Calculation()

        cal.isFirstOperand = true

        isFirstDigit = true

        hasTapEqual = false

        displayResult.text = String(0.0)

        

    }

    override func didReceiveMemoryWarning() {

        super.didReceiveMemoryWarning()

        // Dispose of any resources that can be recreated.

    }

}

Test

Reference

1. Chapter 24, 範例程式五:簡易計算器實作, P24-27, “學會Objective-C 的24堂課“,  蔡明志






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