What properties of music does MPmediaquery see?

I'm trying to figure out whether there is a way to check if a user legally purchased i开发者_C百科ndividual music tracks. Please help! thanks.

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Checking DRM is currently not supported using MPMediaQuery. See the MPMediaItem documentation - media item property keys.

In addition, checking the file's origin is also not possible. To conclude, checking if media was legally purchased is impossible.