If you're trying to translate a set of strings within a project, then I'd strongly recommend converting all string instances such as @"My Title" to the localizable macro:
NSLocalizedString(@"My Title", @"Comment which will appear above My Title, such as ObjC \"My Title\"");
These can then be extracted using the genstrings command line utility, which will generate a strings file with entries like:
/* Comment which will appear above My Title, such as ObjC "My Title" */
@"My Title" = @"My Title";
This means that integrating the translated strings back into your project becomes very simple.
The native way to approach localizing strings within your application is documented here:
https://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/LoadingResources/Strings/Strings.html