I have a Cocoa application that I developed last August (2018). It was working properly under Sierra. When I now debug it with Xcode 10 under Mojave, it works. But when I launch the stand alone application, the view of the application window will turn blank. If you place a push button over the view, it won't appear.
I have finally tracked the source. The application has AVPlayerView as an IBOutlet object wired to a view controller. I am quite certain that it is AVPlayerView that has caused a lot of trouble. If I remove AVPlayerView from the storyboard and also from the view controller, the view of the application window will appear. Does anybody run into the same issue?
More precisely, AVPlayerView causes a serioius issue with Xcode 10.2 or 10.2.1. It doesn't with Xcode 10.1.