改用 swift 寫 ios 比 objective-c 快很多，多國語言的處理這一部份也變簡單很多。
Step 1:
Before starting localization work, make sure you have “Use Base Internationalization” checkmark selected.
Step 2:
Adding New Localization
Access localization sample code:
let alertTitle = NSLocalizedString("Welcome", comment: "")
let alertMessage = NSLocalizedString("Thank you for trying this app, you are a great person!", comment: "")
let cancelButtonText = NSLocalizedString("Cancel", comment: "")
let signupButtonText = NSLocalizedString("Signup", comment: "")
let alert = UIAlertController(title: alertTitle, message: alertMessage, preferredStyle: UIAlertControllerStyle.Alert)
let cancelAction = UIAlertAction(title: cancelButtonText, style: UIAlertActionStyle.Cancel, handler: nil)
let signupAction = UIAlertAction(title: signupButtonText, style: UIAlertActionStyle.Default, handler: nil)
alert.addAction(cancelAction)
alert.addAction(signupAction)
presentViewController(alert, animated: true, completion: nil)
詳全文：
https://medium.com/lean-localization/ios-localization-tutorial-938231f9f881
