Search code examples
swiftstringnumber-formattingswift-playground

Swift playground - How to convert a string with comma to a string with decimal


I'm new in the Swift world.

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

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

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

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

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)

Thank's for your time and your help!


Solution

  • 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"
    

    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"