Associate files with MyGame.exe


I am currently experimenting with loading files into my game during runtime (e.g. images) and alter them, which is working fine. But everytime I want to do this I have to start my packaged game and choose a file within my ingame-filebrowser.

To improve this workflow I tried associating certain file types with my game’s executable so they can be loaded automatically on startup. I got it working for Windows either by dragging the choosen file onto the executable’s icon or via the “Open with…” option to receive the file’s path as a command line argument (calling FCommandLine::Get(),parsing the result and load the file). But if I try the same with the Mac-version of my game it only says that the file type could not be opened and the application starts normal (without having any information in the command line arguments).

Is there a proper way to accomplish file association for a packaged game so it can open certain file types “out of the box” or at least a solution to get it working for Mac?