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

This is the low-level interface to NSMutableAttributedString and in general is only used when you must subclass and override the behavior. You are expected to consume the provided 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.