CS193P 3. Applying MVC

Posted on Edited on

看英文视频加中文字幕，效率也是蛮低的，下个星期六博览网的 iOS 极客班就开学了，希望能够认真高效投入更多时间去学习，一定要学好，找到开发的工作，圆毕业三年的一个梦。

Swift 学习还算顺利，MVC 模式也有所熟悉，就是独自开发和想法实现有困难，暂时停留在看懂和自己写一遍的水平。

还有就是玩手机，刷微博啥的超级浪费时间，因为这个不费脑，玩的也高兴，能够一天不吃饭，也不困，也停不下来。
但是学习或看书，就很费神，容易犯困，这个一定要克服，实在困了就休息10分钟，再继续。

New Calculator Demo

  • Applying MVC to the Calculator
  • enum
  • Simple initializer
  • Returning an Optional
  • Dicionary
  • Tuples

源码如下，待修改：

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//
//  CalculatorBrain.swift
//  Calculator
//
//  Created by Will Ge on 7/11/15.
//  Copyright © 2015 gewill.org. All rights reserved.
//

import Foundation

class CauculatorBrain
{
    // 定义一个枚举类型，来分类表示输入的：运算数、一元运算和二元运算
    enum Op {
        case Operand(Double)
        case UnaryOperation(String, Double -> Double)
        case BinaryOperation(String, (Double, Double) -> Double)
    }
    
    // 定义一个数组来储存所有输入
    var opStack = [Op]()
    
    // 定义已知运算符
    var knownOps = [String:Op]()
    
    // 初始化已知运算符
    init() {
        knownOps["+"] = Op.BinaryOperation("+", +)
        knownOps["−"] = Op.BinaryOperation("−") {$1 - $0}
        knownOps["×"] = Op.BinaryOperation("×", *)
        knownOps["÷"] = Op.BinaryOperation("÷") {$1 / $0}
        knownOps["√"] = Op.UnaryOperation("√", sqrt)
    }
    
    // 定义一个函数，把输入递归取出
    func evaluate(ops: [Op]) -> (result: Double?, remainingOps:[Op]) {
        if !ops.isEmpty {
            var remainingOps = ops
            let op = remainingOps.removeLast()
            switch op {
            case.Operand(let operand):
                return (operand, remainingOps)
            case .UnaryOperation(_, let operation):
                let operandEvaluation = evaluate(remainingOps)
                if let operand = operandEvaluation.result {
                    return (operation(operand), operandEvaluation.remainingOps)
                }
            case .BinaryOperation(_, let operation):
                let op1Evaluation = evaluate(remainingOps)
                if let operand1 = op1Evaluation.result {
                    let op2Evaluation = evaluate(remainingOps)
                    if let operand2 = op2Evaluation.result {
                        return (operation(operand1, operand2), op2Evaluation.remainingOps)
                    }

                    
                }
                
            }
        }
        return (nil, ops)
    }
    
    func evaluate() -> Double? {
        let (result, remainder) = evaluate(opStack)
        print("\(opStack) = \(result) with \(remainder) left over")
        return result
        
    }
    
    // 运算数
    func pushOperand(operand: Double) -> Double? {
        opStack.append(Op.Operand(operand))
        return evaluate()
    }
    
    // 运算符
    func performOperation(symbol: String) -> Double? {
        if let operation = knownOps[symbol] {
            opStack.append(operation)
        }
        return evaluate()
    }
}
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//
//  ViewController.swift
//  Calculator
//
//  Created by Will Ge on 6/28/15.
//  Copyright © 2015 gewill.org. All rights reserved.
//

import UIKit

class ViewController: UIViewController {
    

    @IBOutlet weak var history: UILabel!
    
    @IBOutlet weak var display: UILabel!
    
    
    var userIsInTheMiddleOfTypingANumber: Bool = false
    
    var brain = CauculatorBrain()

    @IBAction func appendDigit(sender: UIButton) {
        let digit = sender.currentTitle!
        if userIsInTheMiddleOfTypingANumber{
              display.text = display.text! + digit
        } else {
            display.text = digit
            userIsInTheMiddleOfTypingANumber = true
        }
    
        print("digit = \(digit)")
    }

    
    
    @IBAction func enter() {
        userIsInTheMiddleOfTypingANumber = false
        if let result = brain.pushOperand(displayValue) {
            displayValue = result
        } else {
            displayValue = 0
        }
        print("pushOperand = \(displayValue)")
        
    }
    
    @IBAction func operate(sender: UIButton) {
        
        if userIsInTheMiddleOfTypingANumber {
            enter()
        }
        if let operation = sender.currentTitle {
            print("\(operation)")
        }
    }
    

    
    var displayValue: Double{
        get {
            return NSNumberFormatter().numberFromString(display.text!)!.doubleValue
        }
        set {
            display.text = "\(newValue)"
            userIsInTheMiddleOfTypingANumber = false
        }
    }
}