xcode 类型的值 ... 没有成员
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原文地址: http://stackoverflow.com/questions/38358904/
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Value of type ... has no member
提问by Mia Maria
Hello I'm new to Swift and I'm learning it on iTunes U, the Stanford University course. And I'm programming a calculator. The instructor in the course video has the same code, software and same version of XCode.
您好，我是 Swift 的新手，我正在斯坦福大学的 iTunes U 课程中学习它。我正在编写一个计算器。课程视频中的讲师具有相同的代码、软件和相同版本的XCode。
Here's the relevant code for ViewController:
这是 ViewController 的相关代码：
import UIKit
class ViewController: UIViewController {
@IBOutlet private weak var display: UILabel!
private var displayValue: Double {
get {
return Double(display.text!)!
}
set {
display.text = String(newValue)
}
}
...
private var brain = calculatorBrain()
@IBAction private func performOperation(sender: UIButton) {
if userIsInTheMiddleOfTyping {
brain.setOperand(displayValue)
userIsInTheMiddleOfTyping = false
}
if let mathematicalSymbol = sender.currentTitle {
brain.performOperation(mathematicalSymbol)
}
displayValue = brain.result
}
}
The error is in the last sentence: displayValue = brain.resultThis is the error: Value of type 'CalculatorBrain' has no value 'result'
错误在最后一句：displayValue = brain.result这是错误：“CalculatorBrain”类型的值没有值“结果”
This is the CalculatorBrain code:
这是 CalculatorBrain 代码：
import Foundation
func multiply(op1: Double, op2: Double) -> Double {
return op1 * op2
}
class calculatorBrain {
private var accumulator = 0.0
func setOperand(operand: Double) {
accumulator = operand
}
var operations: Dictionary<String,Operation> = [
"π" : Operation.Constant(M_PI),
"e" : Operation.Constant(M_E),
"√" : Operation.UnaryOperation(sqrt),
"cos" : Operation.UnaryOperation(cos),
"×" : Operation.BinaryOperation(multiply),
"=" : Operation.Equals
]
enum Operation {
case Constant(Double)
case UnaryOperation((Double) -> Double)
case BinaryOperation((Double, Double) -> Double)
case Equals
}
func performOperation(symbol: String) {
if let operation = operations[symbol] {
switch operation {
case .Constant(let value): accumulator = value
case .UnaryOperation(let function): accumulator = function(accumulator)
case .BinaryOperation(let function):
case .Equals: break
}
}
}
}
struct PendingBinaryOperationInfo {
var BinaryFunction: (Double, Double) -> Double
var firstOperand: Double
}
var result: Double {
get {
return 0.0
}
}
So what's the problem?
所以有什么问题？
采纳答案by Wyetro
You need to move the declaration of result
您需要移动结果的声明
var result: Double {
get {
return 0.0
}
}
here, to inside of the class:
在这里，到课堂内部：
class calculatorBrain {
var result: Double {
get {
return 0.0
}
}
...
}
Since you are defining result outside of the CalculatorBrainclass so you get the error:
由于您是在CalculatorBrain类之外定义结果，因此您会收到错误消息：
Value of type 'CalculatorBrain' has no value 'result'
'CalculatorBrain' 类型的值没有值 'result'
