如何将货币格式化为货币 - Swift 3 [英] How to format a Double into Currency - Swift 3

问题描述

我是Swift编程的新手，我已经在Xcode 8.2中创建了一个简单的小费计算器应用程序，我在下面的 IBAction 中设置了计算。但是当我真正运行我的应用程序，并输入一个金额来计算（如23.45），它会出现超过2个小数位。在这种情况下，如何将它格式化为 .currency ？

pre $ IBAction func calculateButtonTapped（_ sender：Any）{

var tipPercentage：Double {

如果tipAmountSegmentedControl.selectedSegmentIndex == 0 {
return 0.05
} else if tipAmountSegmentedControl.selectedSegmentIndex == 1 {
return 0.10
} else {
return 0.2
}
}

let billAmount：Double ？ = Double（userInputTextField.text！）

if billAmount = billAmount {
let tipAmount = billAmount * tipPercentage
let totalBillAmount = billAmount + tipAmount

tipAmountLabel.text =Tip Amount：$ \（tipAmount）
totalBillAmountLabel.text =Total Bill Amount：$ \（totalBillAmount）
}
}


解决方案您可以使用此字符串初始值设定项，如果您想强制货币为$：

 字符串（格式：Tip Amount：$％。02f，tipAmount）
  

如果您希望它完全依赖于设备的区域设置，您应该使用 NumberFormatter 。这将考虑货币的小数位数，以及正确定位货币符号。例如。 double值2.4会返回es_ES语言环境的2,40€和jp_JP语言环境的¥2。

 让formatter = NumberFormatter（）
 formatter.locale = Locale.current //如果你想强制一个特定的语言环境，将其改为另一个语言环境，否则这是多余的，因为当前的语言环境是默认的
格式化程序.nu​​mberStyle = .currency 
 if formattedTipAmount = formatter.string（from：tipAmount as NSNumber）{
 tipAmountLabel.text =提示金额：\（formattedTipAmount）
} 
  

I'm new to Swift programming and I've been creating a simple tip calculator app in Xcode 8.2, I have my calculations set up within my IBAction below. But when I actually run my app and input an amount to calculate (such as 23.45), it comes up with more than 2 decimal places. How do I format it to .currency in this case?

@IBAction func calculateButtonTapped(_ sender: Any) {

    var tipPercentage: Double {

        if tipAmountSegmentedControl.selectedSegmentIndex == 0 {
            return 0.05
        } else if tipAmountSegmentedControl.selectedSegmentIndex == 1 {
            return 0.10
        } else {
            return 0.2
        }
    }

    let billAmount: Double? = Double(userInputTextField.text!)

    if let billAmount = billAmount {
        let tipAmount = billAmount * tipPercentage
        let totalBillAmount = billAmount + tipAmount

        tipAmountLabel.text = "Tip Amount: $\(tipAmount)"
        totalBillAmountLabel.text = "Total Bill Amount: $\(totalBillAmount)"
    }
}

解决方案

You can use this string initializer if you want to force the currency to $:

String(format: "Tip Amount: $%.02f", tipAmount)

If you want it to be fully dependent on the locale settings of the device, you should use a NumberFormatter. This will take into account the number of decimal places for the currency as well as positioning the currency symbol correctly. E.g. the double value 2.4 will return "2,40 €" for the es_ES locale and "¥ 2" for the jp_JP locale.

let formatter = NumberFormatter()
formatter.locale = Locale.current // Change this to another locale if you want to force a specific locale, otherwise this is redundant as the current locale is the default already
formatter.numberStyle = .currency
if let formattedTipAmount = formatter.string(from: tipAmount as NSNumber) {
    tipAmountLabel.text = "Tip Amount: \(formattedTipAmount)"
}

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