Swift 斯坦福大学斯威夫特课程的斯威夫特计算器

我们在斯坦福大学swift课程中使用计算器，在出现错误时调用方法performOperation（在声明前使用局部变量“performOperation”）。如有任何帮助或建议，我们将不胜感激。谢谢

import UIKit

class ViewController: UIViewController {


@IBOutlet weak var display: UILabel!

var userIsInTheMiddleOfTypingNumber: Bool = false


@IBAction func appendDigit(sender: UIButton){

    let digit = sender.currentTitle!
    if userIsInTheMiddleOfTypingNumber {
        display.text = display.text! + digit
    }
    else {
        display.text = digit
        userIsInTheMiddleOfTypingNumber = true

    }
    //println("digit = \(digit)")
}

@IBAction func operate(sender: UIButton) {
    let operation = sender.currentTitle!
    if userIsInTheMiddleOfTypingNumber {
     enter()
    }
    switch operation {
    case"×": performOperation() { $0 * $1 }  - THIS IS THE CODE WHERE WE GOT ERROR
        //            case"÷":
//            case"+":
//            case"-":
    default: break

    }

   func performOperation(operation: (Double, Double) -> Double) {
        if operandStack.count >= 2 {
            displayValue = operation(operandStack.removeLast(), operandStack.removeLast())
            enter()
        }
    }
}

var operandStack = Array<Double>()

@IBAction func enter() {
    userIsInTheMiddleOfTypingNumber = false
    operandStack.append(displayValue)
    println("operandStack = \(operandStack)")
}

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

}
}

导入UIKit
类ViewController:UIViewController{
@IBVAR显示：UILabel！
var USERISINTHEMIDLEOFTYPINGNUMBER:Bool=false
@iAction func appendDigit（发送方：UIButton）{
让digit=sender.currentTitle！
如果用户是InTheMiddleOftypingNumber{
display.text=display.text！+数字
}
否则{
display.text=数字
USERISINTHEMIDLEOFTYPINGNUMBER=true
}
//println（“数字=\（数字）”）
}
@iAction func operate（发送方：UIButton）{
让操作=sender.currentTitle！
如果用户是InTheMiddleOftypingNumber{
输入（）
}
开关操作{
案例“×”：performOperation（）{$0*$1}-这是我们得到错误的代码
//案例“÷”：
//格“+”：
//案例“-”：
默认值：中断
}
函数执行操作（操作：（双精度，双精度）->双精度）{
如果操作数Stack.count>=2{
displayValue=操作（操作数堆栈.removeLast（），操作数堆栈.removeLast（））
输入（）
}
}
}
变量堆栈=数组（）
@iAction func enter（）{
USERISINTHEMIDLEOFTYPINGNUMBER=false
操作数堆栈.append（显示值）
println（“操作数堆栈=\（操作数堆栈）”）
}
var显示值：双精度{
得到{
返回NSNumberFormatter（）.numberFromString（display.text！）！.doubleValue
}
设置{
display.text=“\（newValue）”
USERISINTHEMIDLEOFTYPINGNUMBER=false
}
}
}

我认为您的performOperation功能应该在@iAction功能之外，如下所示：

 @IBAction func operate(sender: UIButton) {
      let operation = sender.currentTitle!
      if userIsInTheMiddleOfTypingNumber {
      enter()
      }
      switch operation {

            case"×": performOperation() { $0 * $1 }  - THIS IS THE CODE WHERE WE GOT ERROR
      //            case"÷":
      //            case"+":
        //            case"-":
            default: break

            }


       }

        func performOperation(operation: (Double, Double) -> Double)                
        {
               if operandStack.count >= 2 {
               displayValue = operation(operandStack.removeLast(), operandStack.removeLast())
               enter()
               }
        }

---

我认为您的performOperation函数应该在@iAction函数之外，如下所示：

 @IBAction func operate(sender: UIButton) {
      let operation = sender.currentTitle!
      if userIsInTheMiddleOfTypingNumber {
      enter()
      }
      switch operation {

            case"×": performOperation() { $0 * $1 }  - THIS IS THE CODE WHERE WE GOT ERROR
      //            case"÷":
      //            case"+":
        //            case"-":
            default: break

            }


       }

        func performOperation(operation: (Double, Double) -> Double)                
        {
               if operandStack.count >= 2 {
               displayValue = operation(operandStack.removeLast(), operandStack.removeLast())
               enter()
               }
        }

---

我认为您的performOperation函数应该在@iAction函数之外，如下所示：

 @IBAction func operate(sender: UIButton) {
      let operation = sender.currentTitle!
      if userIsInTheMiddleOfTypingNumber {
      enter()
      }
      switch operation {

            case"×": performOperation() { $0 * $1 }  - THIS IS THE CODE WHERE WE GOT ERROR
      //            case"÷":
      //            case"+":
        //            case"-":
            default: break

            }


       }

        func performOperation(operation: (Double, Double) -> Double)                
        {
               if operandStack.count >= 2 {
               displayValue = operation(operandStack.removeLast(), operandStack.removeLast())
               enter()
               }
        }

---

我认为您的performOperation函数应该在@iAction函数之外，如下所示：

 @IBAction func operate(sender: UIButton) {
      let operation = sender.currentTitle!
      if userIsInTheMiddleOfTypingNumber {
      enter()
      }
      switch operation {

            case"×": performOperation() { $0 * $1 }  - THIS IS THE CODE WHERE WE GOT ERROR
      //            case"÷":
      //            case"+":
        //            case"-":
            default: break

            }


       }

        func performOperation(operation: (Double, Double) -> Double)                
        {
               if operandStack.count >= 2 {
               displayValue = operation(operandStack.removeLast(), operandStack.removeLast())
               enter()
               }
        }