To manage strings localization using the default localization system: Localizable.strings

Language.swift

//
//  Language.swift
//
//  Created by Rigoberto Sáenz Imbacuán (https://www.linkedin.com/in/rsaenzi/)
//  Copyright © 2017. All rights reserved.
//

// Dependencies:
// - Language+UIKit: https://gist.github.com/rsaenzi/a575e66f5e617559767e5b523bad2161

import Foundation

class Language {
    
    /**
     This function will return the localized text specified by its key
     */
    static func get(_ key: LanguageKey, from bundle: Bundle = .main) -> String {
        return NSLocalizedString(key.rawValue, tableName: nil, bundle: bundle, value: "", comment: "")
    }
    
    /**
     This function will replace any ocurrence of $0$, $1$, $2$, $3$ ... $X$
     on the localized text, for the specified values
     */
    static func get(_ key: LanguageKey, replacing values: [String], from bundle: Bundle = .main) -> String {
        
        var text = NSLocalizedString(key.rawValue, tableName: nil, bundle: bundle, value: "", comment: "")
        
        guard values.count > 0 else {
            return text
        }
        
        for index in 0..<values.count {
            text = text.replacingOccurrences(of: "$\(index)$", with: values[index])
        }
        return text
    }
    
    /**
     This function will replace any ocurrence of $0$, $1$, $2$, $3$ ... $X$
     on the main localized text, for the localized strings specified by its keys
     */
    static func get(_ key: LanguageKey, replacing keys: [LanguageKey], from bundle: Bundle = .main) -> String {
        
        let values = keys.map { parameterKey -> String in
            return get(parameterKey)
        }
        
        return Language.get(key, replacing: values, from: bundle)
    }
}


// Should be in a different swift file
enum LanguageKey: String {
    case appName
    case OK
    case Cancel
}