如何在计算中使用货币值

Question

我有一个变量来存储我需要在计算中使用的货币值，但是我不知道如何在计算中使用它，因为变量的开头有一个货币符号（例如 £ 2.43，70.82 美元，300.21 欧元）。我曾考虑用任何内容替换第一个字符，但这不起作用，因为有些货币使用多个字符，有些货币在值后面有符号。

有谁知道我如何删除除值本身之外的所有字符？或者另一种将变量纳入计算的方法？ （顺便说一句，我使用的是 Swift）

编辑：

我一直在尝试 NSDecimalNumber 来转换字符串，但是我收到错误消息“NSNumber 无法转换为 NSDecimalNumber”。这是我的代码：

override func viewDidLoad() {
    super.viewDidLoad()
    // Do any additional setup after loading the view, typically from a nib.

    resetButtonNav.enabled = false

    self.navigationController.navigationBar.barTintColor = UIColor.newBlueColor()
    self.tabBarController.tabBar.selectedImageTintColor = UIColor.newBlueColor()
    UINavigationBar.appearance().barTintColor = UIColor.newBlueColor()
    UINavigationBar.appearance().tintColor = UIColor.whiteColor()

    textField.addTarget(self, action: "textFieldDidChange:", forControlEvents: UIControlEvents.EditingChanged)
    self.view.addSubview(textField)

    currencyFormatter.numberStyle = NSNumberFormatterStyle.CurrencyStyle
    currencyFormatter.currencyCode = NSLocale.currentLocale().displayNameForKey(NSLocaleCurrencySymbol, value: NSLocaleCurrencyCode)
}

func textFieldDidChange(textField: UITextField) {
    var text = textField.text.stringByReplacingOccurrencesOfString(currencyFormatter.currencySymbol, withString: "").stringByReplacingOccurrencesOfString(currencyFormatter.groupingSeparator, withString: "").stringByReplacingOccurrencesOfString(currencyFormatter.decimalSeparator, withString: "")
    textField.text = currencyFormatter.stringFromNumber((text as NSString).doubleValue / 100.0)
}

@IBAction func enterBudgetButton(sender : AnyObject) {
    finalUserBudget = textField.text
    budgetName = budgetNameText.text

    var currencyFormatterTest:NSNumberFormatter
    currencyFormatterTest.formatterBehavior = NSNumberFormatterBehavior.Behavior10_4
    currencyFormatterTest.generatesDecimalNumbers = true
    currencyFormatterTest.numberStyle = NSNumberFormatterStyle.CurrencyStyle

    var finalUserBudgetFormatted: NSDecimalNumber = currencyFormatter.numberFromString(finalUserBudget)
    }

Answer 1

您可以使用问题中的此代码：

var text = textField.text.stringByReplacingOccurrencesOfString(currencyFormatter.currencySymbol, withString: "").stringByReplacingOccurrencesOfString(currencyFormatter.groupingSeparator, withString: "").stringByReplacingOccurrencesOfString(currencyFormatter.decimalSeparator, withString: "")
textField.text = currencyFormatter.stringFromNumber((text as NSString).doubleValue / 100.0)

做这个：

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 / 100.0
    return currencyDouble;
}