Code review of forward invocation
I think you trying to overengineer solution a bit. First of all View should not do any stuff at all. View is just a View, sheet of paper. Maximum of view's responsibility is layouting himself. So controller should take care of other view-related stuff. 

In this case I probably prefer to think about gridView as legitimate subview of GameBoard. I really doubt Demetra suffering when you doing something like [self.view.titleLabel sizeToFit]. 

So my advice is to use [self.gameBoard.gridView doStuff]; as simplest and straightforward solution.