In general, you should use the NSAttributedString.GetAttributes methods, which will return a high-level NSDictionary.

This is the low-level interface to NSAttributedString and in general is only useful for subclasses. You are expected to return an IntPtr that represents a handle to an NSDictionary. This API is kept as a low-level API, since it is consumed by NSTextStorage which might call this method thousands of times per character insertion, so it is very important that this is kept as fast as possible, possibly even caching or reusing existing dictionary instances.