Adding custom answer in Mac Spotlight

I saw 开发者_StackOverflow中文版that we have access to calculator in Spotlight! And I wonder how an application can add custom answer like calculator do!

Thank you!

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Simple answer: no, they can't. The only thing you can write is a custom importer your application that enable spotlight to index you application data (as documents or as a database)

Introduction to Spotlight (developer.apple.com)