ja-localized-preview.swift

import Foundation

private class BundleToken {}

extension Bundle {
    static var current: Bundle {
        Bundle(for: BundleToken.self)
    }

    func localized(locale: Locale) -> Bundle? {
        guard let dir = url(forResource: locale.identifier, withExtension: "lproj"),
              let bundle = Bundle(url: dir) else { return nil }

        return bundle
    }
}

private let isSwiftUIPreview: Bool = {
    guard let str = ProcessInfo.processInfo.environment["XCODE_RUNNING_FOR_PREVIEWS"],
          let value = Int(str),
          value != 0 else { return false }
    return true
}()

private let isInterfaceBuilder: Bool = {
    #if TARGET_INTERFACE_BUILDER
    return true
    #else
    return false
    #endif
}()

struct LocalizeKey {
    var value: String

    init(_ value: String) {
        self.value = value
    }

    func string(table: String?) -> String {
        var bundle = Bundle.current

        if isInterfaceBuilder || isSwiftUIPreview,
           let jaBundle = bundle.localized(locale: .ja)
        {
            bundle = jaBundle
        }

        return string(bundle: bundle, table: table)
    }

    func string(bundle: Bundle, table: String?) -> String {
        bundle.localizedString(forKey: value, value: nil, table: table)
    }
}

extension L10n {
  private static func tr(_ table: String, _ key: String, _ args: CVarArg...) -> String {
    let format = LocalizeKey(key).string(table: table)
    return String(format: format, locale: .current, arguments: args)
  }
}

swiftgenの L10n.tr をカスタムテンプレートで差し替える

なぜかLocaleを指定してもだめで、ja bundleを直指定しないといけないんだよな