I created a view in IB I set it's background color to color A I then set it's background color to color B, in viewDidLoad() In iOS 13 simulators, the view shows as expected with color B In iOS 12 simulators, the view shows with color A, which I don't expect, nor want (note: it appears that using didLayoutSubviews works, but why should iOS 12 and 13 behave differently? Either both should work with viewDidLoad, or neither should)