Monotouch access private API with return type

I am trying to port the following code to mirror My App's display to an external display via the VGA adapter.

https://github.com/robterrell/TVOutManager/blob/master/TVOutManager.m

This code optionally accesses UIGetScreenImage(); which returns a CGImageRef object. How can i call this Private API from Monotouch? I want to use this method only for an internal buil开发者_运维问答d of my app for trade shows.

I have seen several solutions, but none talks about how to call a selector with a return type.

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CGImageRef's MonoTouch wrapper, CGImage, has a static property ScreenImage. You can get a screenshot with this property, I haven't used it though.

Details on binding Objective-C objects (including returning selector values) can be found here: http://monotouch.net/index.php?title=Documentation/Binding_New_Objective-C_Types/Binding_Details&highlight=bind