Function MDCopyLabelsMatchingExpression 

pub unsafe extern "C-unwind" fn MDCopyLabelsMatchingExpression(
    simple_query_string: Option<&CFString>,
) -> Option<CFRetained<CFArray>>

Available on crate feature MDLabel only.

Copy the list of labels matching the specified query expression.

Parameter simpleQueryString: The query expression string.

Returns: A CFArrayRef containing all of the matching labels, or NULL on failure.

Safety

simple_query_string might not allow None.