iOS - Currency Formatters Playground

CurrencyFormatters.swift

import Foundation

extension Locale {
    static var customer = Locale.ptBR

    static let enUS = Locale(identifier: "en_US")
    static let ptBR = Locale(identifier: "pt_BR")
    static let esMX = Locale(identifier: "es_MX")
    static let jaJP = Locale(identifier: "ja_JP")
    static let frCA = Locale(identifier: "fr_CA")
    static let zhCN = Locale(identifier: "zh_CN")
}

class CurrencyFormatter: NumberFormatter {
    override init() {
        super.init()
        numberStyle = .currency
        roundingMode = .down // 5.089 -> $5.08 or -5.089 -> -5.08
    }

    convenience init(locale: Locale) {
        self.init()
        self.locale = locale
    }

    convenience init(locale: Locale, currencyCode: String) {
        self.init(locale: locale)
        self.currencyCode = currencyCode
    }

    required init?(coder aDecoder: NSCoder) {
        super.init(coder: aDecoder)
    }
}

class TaggedCurrencyFormatter: CurrencyFormatter {
    let tag: String
    var openTag: String { return "<\(tag)>" }
    var closeTag: String { return "</\(tag)>" }

    override var locale: Locale! {
        willSet {
            positivePrefix = nil
            negativePrefix = nil
            positiveSuffix = nil
            negativeSuffix = nil
            currencyDecimalSeparator = nil
        }
        didSet {
            let hasDecimalSeparator = positiveFormat.contains(".")
            if hasDecimalSeparator {
                currencyDecimalSeparator = closeTag + currencyDecimalSeparator
            } else {
                positiveSuffix = positiveSuffix + closeTag
                negativeSuffix = negativeSuffix + closeTag
            }
        }
    }

    init(tag: String) {
        self.tag = tag
        super.init()
    }

    convenience init(tag: String, locale: Locale) {
        self.init(tag: tag)
        self.locale = locale
    }

    convenience init(tag: String, locale: Locale, currencyCode: String) {
        self.init(tag: tag, locale: locale)
        self.currencyCode = currencyCode
    }

    required init?(coder aDecoder: NSCoder) {
        tag = "bold"
        super.init(coder: aDecoder)
    }

    override func string(from number: NSNumber) -> String? {
        // When updating both prefixes the final format fails (only partial)
        let isPositiveNumber = number.compare(0) != .orderedAscending
        let prefixKeyPath: ReferenceWritableKeyPath = isPositiveNumber ?
            \CurrencyFormatter.positivePrefix :
            \CurrencyFormatter.negativePrefix

        self[keyPath: prefixKeyPath] = self[keyPath: prefixKeyPath] + openTag
        let result = super.string(from: number)
        self[keyPath: prefixKeyPath] = nil
        return result
    }
}

let sharedFormatter = CurrencyFormatter()
func getFormatter(locale: Locale) -> NumberFormatter {
    sharedFormatter.locale = locale
    return sharedFormatter
}

let sharedBoldFormatter = TaggedCurrencyFormatter(tag: "bold")
func getBoldFormatter(for locale: Locale) -> NumberFormatter {
    sharedBoldFormatter.locale = locale
    return sharedBoldFormatter
}

let everyLocale = Locale.availableIdentifiers.lazy.map(Locale.init(identifier:))
let allLocales = [Locale.enUS, .ptBR, .esMX, .zhCN, .frCA, .jaJP]

func all(_ number: NSNumber, locales: [Locale] = allLocales) {
    print("Value:", number)
    print(locales
        .map {
            let currencyCode = "USD"
            let identifier = $0.identifier + ": "
            let formatted = [getFormatter(locale: $0).string(from: number)!,
                             getBoldFormatter(for: $0).string(from: number)!,
                             CurrencyFormatter(locale: $0, currencyCode: currencyCode).string(from: number)!,
                             TaggedCurrencyFormatter(tag: "bold", locale: $0, currencyCode: currencyCode).string(from: number)!]
                .joined(separator: "\t | ")
            return identifier + formatted
        }
        .joined(separator: "\n"))
    print()
}

all(0)
all(1234567.809)
all(-1234567.809)
//all(123.456)
//all(-123.456)
//all(123.45)
//all(-123.45)

func meta(_ f: NumberFormatter) {
    print(f.locale.identifier)
    print("formats:", f.positiveFormat, f.negativeFormat)
    print("decimal:", f.decimalSeparator, f.currencyDecimalSeparator)
    print("group:", f.groupingSeparator, f.currencyGroupingSeparator)
    print("positive:", f.positivePrefix, f.positiveSuffix)
    print("negative:", f.negativePrefix, f.negativeSuffix)
    print()
}
//allLocales.forEach(meta)