按下@IBAction 按钮后Swift 保持变量

Question

我正在研究“小费计算器”，遇到了问题。一旦我将信息放入 UITextField 并运行应用程序，它就会正确计算。然后我将小费 slider 值或人数调整为另一个值，再次点击计算，tabBill 中的变量与所有其他值一起被清除。如果我注释掉货币格式化程序，它将执行我想要的操作。我怎样才能让变量保持它的值，这样我就可以对一个字段进行调整，然后在保持货币格式的同时再次运行它？请非常具体，因为我对很多此类术语都很陌生。

@IBAction func calculateButtonPress(sender: AnyObject) {
        println("refresh requested")

        let numberFormatter = NSNumberFormatter()
        numberFormatter.numberStyle = NSNumberFormatterStyle.CurrencyStyle

        let tabBill = (billAmountTextField.text as NSString).doubleValue
        billAmountTextField.text = numberFormatter.stringFromNumber(tabBill)
        billAmountTextField.text != "\(tabBill)"

        peoplePaying = (numberOfPeoplePaying.text as NSString).doubleValue

        tipTotal = tabBill * tipPercent

        tipPerPerson = Double(tipTotal) / Double(peoplePaying)
        tipPerPersonAmount.text = "\(tipPerPerson)"
        tipPerPersonAmount.text = numberFormatter.stringFromNumber(tipPerPerson)

        totalPerPersonDue = (tabBill + tipTotal) / peoplePaying
        totalPerPerson.text = "\(totalPerPersonDue)"
        totalPerPerson.text = numberFormatter.stringFromNumber(totalPerPersonDue)

        tipTotalAmount.text = numberFormatter.stringFromNumber(tipTotal)
        totalBillWithTip = Double(tabBill)+Double(tipTotal)

        totalBillAmountWithTip.text = numberFormatter.stringFromNumber(totalBillWithTip)

        //console output
        println("tabBill:\(tabBill)", "sliderValue:\(sliderValue)", "tipPercent:\(tipPercent)", "tipTotal:\(tipTotal)", "tipPerPerson:\(tipPerPerson)", "peoplePaying:\(peoplePaying)", "totalPerPersonDue:\(totalPerPersonDue)", "totalBillWithTip:\(totalBillWithTip)")
}

Answer 1

第一次运行该应用程序时，文本字段中有一个 double 值(假设为 10.00)，因此转换工作正常，但随后您将此 double 值转换为货币并保存到文本字段中(现在它的值为 $10.00) ，这个新的文本字段不能像你第一次做的那样转换成 double ，尝试通过这个函数运行文本字段的值:

func currencyStringAsDouble(currencyString: String) -> Double {
    let currencyFormatter = NSNumberFormatter()
    currencyFormatter.numberStyle = NSNumberFormatterStyle.CurrencyStyle
    let cleanedString = currencyString.stringByReplacingOccurrencesOfString(currencyFormatter.currencySymbol, withString: "").stringByReplacingOccurrencesOfString(currencyFormatter.groupingSeparator, withString: "").stringByReplacingOccurrencesOfString(currencyFormatter.decimalSeparator, withString: "")
    let currencyDouble = (text as NSString).doubleValue
    return currencyDouble;
}

此函数会再次将您的货币字符串转换回双倍数，在您的情况下您会这样做:

let tabBill = currencyStringAsDouble(billAmountTextField.text)

因此您的最终代码将如下所示:

@IBAction func calculateButtonPress(sender: AnyObject) { println("刷新请求")

    let numberFormatter = NSNumberFormatter()
    numberFormatter.numberStyle = NSNumberFormatterStyle.CurrencyStyle

    //***Only line that change***//
    let tabBill = currencyStringAsDouble(billAmountTextField.text)

    billAmountTextField.text = numberFormatter.stringFromNumber(tabBill)
    billAmountTextField.text != "\(tabBill)"

    peoplePaying = (numberOfPeoplePaying.text as NSString).doubleValue

    tipTotal = tabBill * tipPercent

    tipPerPerson = Double(tipTotal) / Double(peoplePaying)
    tipPerPersonAmount.text = "\(tipPerPerson)"
    tipPerPersonAmount.text = numberFormatter.stringFromNumber(tipPerPerson)

    totalPerPersonDue = (tabBill + tipTotal) / peoplePaying
    totalPerPerson.text = "\(totalPerPersonDue)"
    totalPerPerson.text = numberFormatter.stringFromNumber(totalPerPersonDue)

    tipTotalAmount.text = numberFormatter.stringFromNumber(tipTotal)
    totalBillWithTip = Double(tabBill)+Double(tipTotal)

    totalBillAmountWithTip.text = numberFormatter.stringFromNumber(totalBillWithTip)

    //console output
    println("tabBill:\(tabBill)", "sliderValue:\(sliderValue)", "tipPercent:\(tipPercent)", "tipTotal:\(tipTotal)", "tipPerPerson:\(tipPerPerson)", "peoplePaying:\(peoplePaying)", "totalPerPersonDue:\(totalPerPersonDue)", "totalBillWithTip:\(totalBillWithTip)")
}

//Add new function to convert currency to double
 func currencyStringAsDouble(currencyString: String) -> Double {
        let cleanedString = currencyString.stringByReplacingOccurrencesOfString(currencyFormatter.currencySymbol, withString: "").stringByReplacingOccurrencesOfString(currencyFormatter.groupingSeparator, withString: "").stringByReplacingOccurrencesOfString(currencyFormatter.decimalSeparator, withString: "")
        let currencyDouble = (text as NSString).doubleValue
        return currencyDouble;
}