I can confirm that with newer versions of iOS it's pickerView.subviews.last. You can set its backgroundColor to any color, including clear.

There are some interesting solutions proposed here: https://stackoverflow.com/questions/43819455/xcode-not-displaying-compile-errors I managed to fix it by using DevCleaner from the app store to delete everything.

Clearing cache fixed it for me.

Thanks for posting this, it's helpful.

If you go to edit the target then Run, is it set to Launch automatically or does it say Wait for executable to be launched? It might be that you need to launch it manually.