The String extension that uses a key to get the localized string of itself.

String+InAppLocalization.swift

import Foundation

extension String {
    
    /// Get the localized string using the key.
    ///
    /// - Parameter key: The localization key.
    /// - Returns: The localized string if there exists the value of the key. Otherwise, return the string itself.
    func localized(key: String) -> String {
        if let localizedString = InAppLocalizationManager.shared.localizedString(key) {
            return localizedString
        }
        return self
    }

}