What are “Imported UTIs” in Xcode 4?

问题:

In Xcode 4 there are lists for "document types", "imported UTIs" and "exported UTIs" in project info. I know what document types are, but what are the imported/exported UTIs for? Do I need to declare every document type as a imported/exported UTI as well? I use UTIs.

Thanks.

回答1:

Your application declares the UTIs it uses as imported or exported UTIs.

Exported UTIs are the UTIs for which your application is authoritative. That is, document types which you own and define.

Imported UTIs are document types which you know about but for which some other application may be authoritative.

The difference in practice is that if an application declares an imported UTI, and some other application declares the same UTI but as an exported UTI, the OS will use the exported UTI data over the imported UTI data.

More info