I've completed a simple app that plays 3D video. Now, I'm trying to make it open files from the menu, as well as using the Cmd-O keyboard shortcut.
But the "Open" menu item in the "File" menu is gray - I don't know exactly what this means, but it seems that the current form of the app doesn't support openning files.
I've had a func application(_ application: NSApplication, openFile filename: String) -> Bool function in my app delegate, I've had a CFBundleDocumentTypes with an entry of the MIME type of "video/mp4".
What am I doing wrong?