Returns the UTI for the preview request.
- macOS 10.0–10.15Deprecated
The preview request object.
The UTI of the associated preview request; returns
NULL if the UTI is not available. You should explicitly release this object when it is no longer needed.
Thread-safety: This function should be called in the same thread as the preview request is made in; generally, this is the same thread in which the GeneratePreviewForURL callback was invoked.