After upgrading Xcode to Version 11.4 (11E146) on iOS 13.4 barTintColor only changes through the storyboard. In the code, changes are ignored.
self.navigationController.navigationBar.barTintColor = UIColor.redColor;
Also a problem with the color of the title.
https://stackoverflow.com/questions/60847296/unchanged-bartintcolor-uinavigationbar-on-ios-13-4