ios - 将代码从 View Controller 中取出并将其移动到执行所有 Swift 功能的 "Brain"

Question

我最近在经历了很多错误之后完成了我的第一个应用程序(它是一个计算器)，我了解到在 ViewController 中执行任何计算通常是不明智的，而是在一个单独的文件中完成它。我的主要问题是:

是否可以将我的每个函数中的当前代码放入一个 swift 类中来执行它们？

然后我可以在 View Controller 中的每个函数下实现 class.function()。

我想这样做的原因是为了将来我可以只上一个计算器类(class)，我也会知道如何在未来的每个项目中做到这一点，我也将能够使用这些类(class)。

我尝试过试验，但我似乎无法在我的其他文件中引用 lbl.output。

//
//  ViewController.swift
//  MyCalculator
//
//  Created by Kevin Maldjian on 2/6/17.
//  Copyright © 2017 Kevin Maldjian. All rights reserved.
//

import UIKit
import Foundation

class ViewController: UIViewController {
    var num1 = ""
    var num2 = ""
    var finalString = ""
    var isFirstNumber = true
    var safeToAdd = true
    var hasFinalString = false
    var isClear = true
    var hasDecimal = false
    var doubleChecker = 0
    var hasSecondDecimal = false

    @IBOutlet weak var LBLOutput: UILabel!

    @IBAction func btrNumberClick(_ sender: UIButton) {
        if isClear {
            LBLOutput.text = ""
            isClear = false
        }
        let currentText = LBLOutput.text!
        let textLabel = sender.titleLabel?.text
        if let text = textLabel {
            switch text {
            case "+", "x", "/", "-","%":
                if hasFinalString {
                    return
                }
                finalString = text
                isFirstNumber = false
                hasFinalString = true
                safeToAdd = true
                LBLOutput.text = "\(currentText) \(finalString) "
                break
            case "=":
                if !hasFinalString
                {break}
                isFirstNumber = true
                hasFinalString = false
                isClear = true
                var result = calculate()
                if result.truncatingRemainder(dividingBy:1)  == 0
                {
                    result = (result)
                }
                LBLOutput.text = "\(result)"
                num1 = "\(result)"
                safeToAdd = false
                hasSecondDecimal = false
                hasDecimal = false
                break
            case ".":
                if !safeToAdd{
                    num1 = ""
                    LBLOutput.text = ""
                    num1 = "\(num1)\(text)"
                    LBLOutput.text = LBLOutput.text! + num1
                    safeToAdd = true

                } else if isFirstNumber{
                    if hasDecimal
                    {break}
                    LBLOutput.text = ""
                    num1 = "\(num1)\(text)"
                    LBLOutput.text = LBLOutput.text! + num1
                    hasDecimal = true

                }else{
                    if hasSecondDecimal
                    {break}
                    num2 = "\(num2)\(text)"
                    LBLOutput.text = "\(currentText)\(text)"
                    hasSecondDecimal = true


                }
                break

            default:
                if !safeToAdd{
                    num1 = ""
                    LBLOutput.text = ""
                    num1 = "\(num1)\(text)"
                    LBLOutput.text = LBLOutput.text! + num1
                    safeToAdd = true

                } else if isFirstNumber{
                    LBLOutput.text = ""
                    num1 = "\(num1)\(text)"
                    LBLOutput.text = LBLOutput.text! + num1

                }else{ num2 = "\(num2)\(text)"
                    LBLOutput.text = "\(currentText)\(text)"


                }
                break;
            }
        }
    }

    func calculate() -> Double {
        let firstNumber = Double(num1)!
        let secondNumber = Double(num2)!
        num1 = ""
        num2 = ""
        isClear = false
        switch finalString {
        case "+":
            return firstNumber + secondNumber
        case "-":
            return firstNumber - secondNumber
        case "x":
            return firstNumber * secondNumber
        case "/":
            return firstNumber / secondNumber
        case "%":
            return (firstNumber * 100) / secondNumber
        default:
            return 0
        }
    }

    @IBAction func clearTheLabel(_ sender: Any) {
        num1 = ""
        num2 = ""
        LBLOutput.text = "0"
        isClear = true
    }

    @IBAction func goNegative(_ sender: Any){
        var negativeChecker = Double(num1)!
        if negativeChecker > 0
        {    num1 = ("-" + num1)
            LBLOutput.text = num1
        }else{
            negativeChecker = (-2 * negativeChecker) + negativeChecker
            num1 = String(negativeChecker)
            LBLOutput.text = String(negativeChecker)
        }
    }

    @IBAction func squareRoot(_ sender: Any) {
        let squareRootX = sqrt(Double(LBLOutput.text!)!)
        num1 = String(squareRootX)
        LBLOutput.text = String(squareRootX)
    }
}

Answer 1

与其尝试从“大脑”类调用 LBLOutput.text = x，不如让大脑函数返回正确的计算值，并使用 viewController 将其设置为文本在你的标签中。 如果您遵循“MVC”，这就是 viewController 的预期用途。

例如，如果您的 Brain 类有一个名为 sum 的函数，您可以像这样设置它:

class func sum(x: Int, y: Int) -> Int {
    return x + y
}

在您的 viewController 中，您可以说 LBLOutput.text = "\(Brain.sum(x, y: y)"