an NSNumber object should do it.
Laurent, thanks for the answer. I believed that was the case. What about the delegate method case, though? I mean, the framework I'm playing with expects a certain delegate method and passes C unsigned ints to it: http://github.com/lukhnos/objectiveflickr/blob/b480aa39fa0e96f40a1b44523e0b6... In this case I have no say in the Objective-C side of things. I write only Ruby code. The only thing I can do is to not implement the method at all (and lose some functionality provided by the framework). Obviously in an open-source environment I'm free to patch the library to my liking, but that's not optimal and not always possible. There may be more cases like this. Unless there is a policy on not using primitive types in delegates (is there?), more libraries (or maybe Cocoa itself?) can have problems with MacRuby. -- Regards, Łukasz Adamczak