Swift Playground-如何将逗号字符串转换为十进制字符串 [英] Swift playground - How to convert a string with comma to a string with decimal

问题描述

我是Swift世界的新手。

I'm new in the Swift world.

如何将带逗号的字符串转换为带小数的字符串？

How can I converting a String with a comma to a String with a decimal?

带点（。）的代码可以正常工作

The code work's fine with a dot (.)

问题是当我使用逗号（，）... ： var price

The problem is when I'm using a comma (,) ... with: var price

问题的根源是小数法语键盘使用逗号（，）而不是点（。）

The origin of the problem is the Decimal french keyboard use a comma (,) instead of a dot (.)

如果是关键，则不知道如何使用 NSNumberFormatter 或 generatesDecimalNumbers 。可能有不止一种选择。

Don't know exactly how to use NSNumberFormatter or generatesDecimalNumbers if it's the key. There's probebly more than one options.

//The answer change if "2,25" or "2.25" is used.

var price      : String = "2,25"
var priceFloat = (price as NSString).floatValue

//I need to have 2.25 as answer.

var costString = String(format:"%.2f", priceFloat)

感谢您的时间和帮助！

推荐答案

更新： Xcode 8.2.1•Swift 3.0.2
您可以使用NumberFormatter（）将字符串转换为数字。您只需要指定小数点分隔符，如下所示：

update: Xcode 8.2.1 • Swift 3.0.2 You can use NumberFormatter() to convert your string to number. You just need to specify the decimalSeparator as follow:

extension String {
    static let numberFormatter = NumberFormatter()
    var doubleValue: Double {
        String.numberFormatter.decimalSeparator = "."
        if let result =  String.numberFormatter.number(from: self) {
            return result.doubleValue
        } else {
            String.numberFormatter.decimalSeparator = ","
            if let result = String.numberFormatter.number(from: self) {
                return result.doubleValue
            }
        }
        return 0
    }
}


"2.25".doubleValue // 2.25
"2,25".doubleValue // 2.25

let price = "2,25"
let costString = String(format:"%.2f", price.doubleValue)   // "2.25"

您还应该使用NumberFormat进行货币格式化，因此创建一个扩展FloatingPoint协议的只读计算属性货币，以从String doubleValue属性返回格式化的字符串。

You should do the currency formatting also with NumberFormat, so create a read-only computed property currency extending FloatingPoint protocol to return a formatted string from the String doubleValue property.

extension NumberFormatter {
    convenience init(style: Style) {
        self.init()
        self.numberStyle = style
    }
}
extension Formatter {
    static let currency = NumberFormatter(style: .currency)
}
extension FloatingPoint {
    var currency: String {
        return Formatter.currency.string(for: self) ?? ""
    }
}

---

---

let costString = "2,25".doubleValue.currency   // "$2.25"

---

---

Formatter.currency.locale = Locale(identifier: "en_US")
"2222.25".doubleValue.currency    // "$2,222.25"
"2222,25".doubleValue.currency    // "$2,222.25"

Formatter.currency.locale = Locale(identifier: "pt_BR")
"2222.25".doubleValue.currency    // "R$2.222,25"
"2222,25".doubleValue.currency    // "R$2.222,25"

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