Returns the options specified for the preview request.
- macOS 10.0–10.15Deprecated
A preview request object.
A dictionary containing the properties specified for the preview request. See Preview Properties for supported options. You should explicitly release this object when it is no longer needed.
The client sets options in the preview request to give hints to the generator. For macOS 10.5, no options are supported.
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.