EnlishLocalizationFallback

private let bundle = Bundle.main
private let tableName = "Localizable"

private let cachedEnglishLocalizations: [String: String] = {
    let bundleURL = bundle.bundleURL as CFURL
    let bundle = CFBundleCreate(nil, bundleURL)

    let cfTableName = "Localizable" as CFString
    let fileExtension = "strings" as CFString
    let englishBundleDirName = "En" as CFString

    guard let url = CFBundleCopyResourceURLForLocalization(
        bundle, cfTableName, fileExtension, nil, englishBundleDirName
    ) else {
        fatalError()
    }

    let plistData = try! Data(contentsOf: url as URL)
    let englishLocalizations = try! PropertyListDecoder().decode(
        [String: String].self, from: plistData)

    return englishLocalizations
}()

extension String {
    func localize() -> String {
        let localizedString = NSLocalizedString(
            self, tableName: tableName, bundle: bundle, value: "", comment: ""
        )
        if localizedString == self, let englishVersion = cachedEnglishLocalizations[self] {
            // fall back to English version
            return englishVersion
        } else {
            return localizedString
        }
    }
}