I know Xcode / objective-c to make your project available in multi-languages. And have the experience.
When i make your project files ready to be translated, we can make not only spanish version but for example russian version as well.
1. You should provide me the translated texts. If you want me to have strings translated, i should add translation fees for each language (will be paid to translators)
2. If you want me to prepare the application review images for new language, i should also add a small fee.