Struggling with NSNumberFormatter in Swift for currency

问题

I am creating a budget app that allows the user to input their budget as well as transactions. I need to allow the user to enter both pence and pounds from separate text fields and they need to be formatted together with currency symbols. I have this working fine at the moment but would like to make it localised as currently it only works with GBP. I have been struggling to covert NSNumberFormatter examples from Objective C to Swift.

My first issue is the fact that I need to set the placeholders for the input fields to be specific to the users location. Eg. Pounds and Pence, Dollars and Cents etc...

The second issue is that the values inputted in each of the text fields such as 10216 and 32 need to be formatted and the currency symbol specific to the users location needs to be added. So it would become £10,216.32 or $10,216.32 etc...

Also, I need to use the result of the formatted number in a calculation. So how can I do this without running into issues without running into issues with the currency symbol?

Any help would be much appreciated.

回答1:

Here's an example on how to use it on Swift 3. ( Edit: Works in Swift 4 too )

let price = 123.436 as NSNumber

let formatter = NumberFormatter()
formatter.numberStyle = .currency
// formatter.locale = NSLocale.currentLocale() // This is the default
// In Swift 4, this ^ has been renamed to simply NSLocale.current
formatter.string(from: price) // "$123.44"

formatter.locale = Locale(identifier: "es_CL")
formatter.string(from: price) // $123"

formatter.locale = Locale(identifier: "es_ES")
formatter.string(from: price) // "123,44 €"

Here's the old example on how to use it on Swift 2.

let price = 123.436

let formatter = NSNumberFormatter()
formatter.numberStyle = .CurrencyStyle
// formatter.locale = NSLocale.currentLocale() // This is the default
formatter.stringFromNumber(price) // "$123.44"

formatter.locale = NSLocale(localeIdentifier: "es_CL")
formatter.stringFromNumber(price) // $123"

formatter.locale = NSLocale(localeIdentifier: "es_ES")
formatter.stringFromNumber(price) // "123,44 €"

回答2:

Swift 3:

If you are looking for a solution that gives you:

"5" = "$5"
"5.0" = "$5"
"5.00" = "$5"
"5.5" = "$5.50"
"5.50" = "$5.50"
"5.55" = "$5.55"
"5.234234" = "5.23"

Please use the following:

func cleanDollars(_ value: String?) -> String {
    guard value != nil else { return "$0.00" }
    let doubleValue = Double(value!) ?? 0.0
    let formatter = NumberFormatter()
    formatter.currencyCode = "USD"
    formatter.currencySymbol = "$"
    formatter.minimumFractionDigits = (value!.contains(".00")) ? 0 : 2
    formatter.maximumFractionDigits = 2
    formatter.numberStyle = .currencyAccounting
    return formatter.string(from: NSNumber(value: doubleValue)) ?? "$\(doubleValue)"
}

回答3:

I have implemented the solution provided by @NiñoScript as an extension as well:

Extension

// Create a string with currency formatting based on the device locale
//
extension Float {
    var asLocaleCurrency:String {
        var formatter = NSNumberFormatter()
        formatter.numberStyle = .CurrencyStyle
        formatter.locale = NSLocale.currentLocale()
        return formatter.stringFromNumber(self)!
    }
}

Usage:

let amount = 100.07
let amountString = amount.asLocaleCurrency
print(amount.asLocaleCurrency())
// prints: "$100.07"

Swift 3

    extension Float {
    var asLocaleCurrency:String {
        var formatter = NumberFormatter()
        formatter.numberStyle = .currency
        formatter.locale = Locale.current
        return formatter.string(from: self)!
    }
}

回答4:

Xcode 9 • Swift 4

extension Locale {
    static let br = Locale(identifier: "pt_BR")
    static let us = Locale(identifier: "en_US")
    static let uk = Locale(identifier: "en_UK")
}

extension NumberFormatter {
    convenience init(style: Style, locale: Locale = .current) {
        self.init()
        self.locale = locale
        numberStyle = style
    }
}

extension Formatter {
    static let currency = NumberFormatter(style: .currency)
    static let currencyUS = NumberFormatter(style: .currency, locale: .us)
    static let currencyBR = NumberFormatter(style: .currency, locale: .br)
}

extension Numeric {   // for Swift 3 use FloatingPoint or Int
    var currency: String {
        return Formatter.currency.string(for: self) ?? ""
    }
    var currencyUS: String {
        return Formatter.currencyUS.string(for: self) ?? ""
    }
    var currencyBR: String {
        return Formatter.currencyBR.string(for: self) ?? ""
    }
}

let price = 1.99

print(Formatter.currency.locale)  // "en_US (current)\n"
print(price.currency)             // "$1.99\n"

Formatter.currency.locale = .br
print(price.currency)  // "R$1,99\n"

Formatter.currency.locale = .uk
print(price.currency)  // "£1.99\n"

print(price.currencyBR)  // "R$1,99\n"
print(price.currencyUS)  // "$1.99\n"

回答5:

Details

Xcode 10.2.1 (10E1001), Swift 5

Solution

import Foundation

class CurrencyFormatter {
    static var outputFormatter = CurrencyFormatter.create()
    class func create(locale: Locale = Locale.current,
                      groupingSeparator: String? = nil,
                      decimalSeparator: String? = nil,
                      style: NumberFormatter.Style = NumberFormatter.Style.currency) -> NumberFormatter {
        let outputFormatter = NumberFormatter()
        outputFormatter.locale = locale
        outputFormatter.decimalSeparator = decimalSeparator ?? locale.decimalSeparator
        outputFormatter.groupingSeparator = groupingSeparator ?? locale.groupingSeparator
        outputFormatter.numberStyle = style
        return outputFormatter
    }
}

extension Numeric {
    func toCurrency(formatter: NumberFormatter = CurrencyFormatter.outputFormatter) -> String? {
        guard let num = self as? NSNumber else { return nil }
        var formatedSting = formatter.string(from: num)
        guard let locale = formatter.locale else { return formatedSting }
        if let separator = formatter.groupingSeparator, let localeValue = locale.groupingSeparator {
            formatedSting = formatedSting?.replacingOccurrences(of: localeValue, with: separator)
        }
        if let separator = formatter.decimalSeparator, let localeValue = locale.decimalSeparator {
            formatedSting = formatedSting?.replacingOccurrences(of: localeValue, with: separator)
        }
        return formatedSting
    }
}

Usage

let price = 12423.42
print(price.toCurrency() ?? "")

CurrencyFormatter.outputFormatter = CurrencyFormatter.create(style: .currencyISOCode)
print(price.toCurrency() ?? "nil")

CurrencyFormatter.outputFormatter = CurrencyFormatter.create(locale: Locale(identifier: "es_ES"))
print(price.toCurrency() ?? "nil")

CurrencyFormatter.outputFormatter = CurrencyFormatter.create(locale: Locale(identifier: "de_DE"), groupingSeparator: " ", style: .currencyISOCode)
print(price.toCurrency() ?? "nil")

CurrencyFormatter.outputFormatter = CurrencyFormatter.create(groupingSeparator: "_", decimalSeparator: ".", style: .currencyPlural)
print(price.toCurrency() ?? "nil")

let formatter = CurrencyFormatter.create(locale: Locale(identifier: "de_DE"), groupingSeparator: " ", decimalSeparator: ",", style: .currencyPlural)
print(price.toCurrency(formatter: formatter) ?? "nil")

Results

$12,423.42
USD12,423.42
12.423,42 €
12 423,42 EUR
12_423.42 US dollars
12 423,42 Euro

回答6:

Updated for Swift 4 from @Michael Voccola's answer:

extension Double {
    var asLocaleCurrency: String {
        let formatter = NumberFormatter()
        formatter.numberStyle = .currency
        formatter.locale = Locale.current

        let formattedString = formatter.string(from: self as NSNumber)
        return formattedString ?? ""
    }
}

Note: no force-unwraps, force-unwraps are evil.

回答7:

Swift 4 TextField Implemented

var value = 0    
currencyTextField.delegate = self

func numberFormatting(money: Int) -> String {
        let formatter = NumberFormatter()
        formatter.numberStyle = .currency
        formatter.locale = .current
        return formatter.string(from: money as NSNumber)!
    }

currencyTextField.text = formatter.string(from: 50 as NSNumber)!

func textFieldDidEndEditing(_ textField: UITextField) {
    value = textField.text
    textField.text = numberFormatting(money: Int(textField.text!) ?? 0 as! Int)
}

func textFieldDidBeginEditing(_ textField: UITextField) {
    textField.text = value
}

回答8:

Swift 4

formatter.locale = Locale.current

if you want to change locale you can do it like this

formatter.locale = Locale.init(identifier: "id-ID")

// This is locale for Indonesia locale. if you want use as per mobile phone area use it as per upper mention Locale.current

//MARK:- Complete code
let formatter = NumberFormatter()
formatter.numberStyle = .currency
    if let formattedTipAmount = formatter.string(from: Int(newString)! as 
NSNumber) { 
       yourtextfield.text = formattedTipAmount
}

回答9:

add this function

func addSeparateMarkForNumber(int: Int) -> String {
var string = ""
let formatter = NumberFormatter()
formatter.locale = Locale.current
formatter.numberStyle = .decimal
if let formattedTipAmount = formatter.string(from: int as NSNumber) {
    string = formattedTipAmount
}
return string
}

using:

let giaTri = value as! Int
myGuessTotalCorrect = addSeparateMarkForNumber(int: giaTri)

回答10:

extension Float {
    var convertAsLocaleCurrency :String {
        var formatter = NumberFormatter()
        formatter.numberStyle = .currency
        formatter.locale = Locale.current
        return formatter.string(from: self as NSNumber)!
    }
}

This working for swift 3.1 xcode 8.2.1

来源：https://stackoverflow.com/questions/24960621/struggling-with-nsnumberformatter-in-swift-for-currency

标签

swift

nsnumberformatter