You are printing a number not a string Xcode 9 • Swift 4

String-To-Price-Extension.swift

extension String {
    var twoFractionDigits: String {
        let styler = NumberFormatter()
        styler.minimumFractionDigits = 2
        styler.maximumFractionDigits = 2
        styler.numberStyle = .currency
        let converter = NumberFormatter()
        converter.decimalSeparator = "."
        if let result = converter.number(from: self) {
            return styler.string(for: result) ?? ""
        }
        return ""
    }
}