title: iOS 15 UITabBarController's tabBar background color turns black
body: <p><code>tabBar.barTintColor</code> can't be changed in iOS 15 beta 4.</p>
  <p><strong>Background</strong>. We have an app in App Store and each year before the new iOS major version releases we download the iOS beta and test our app to fix the issues beforehand.</p>
  <p><strong>Our problem</strong>. This year when testing in iOS 15 beta 4 we found the UITabBarController's tabBar background color turns black and makes the item (both icon and title) hard to read. In our code we had self.tabBar.barTintColor = .white and this line of code doesn't work in iOS 15.</p>
  <p><strong>Our attempts</strong>. I search online and found a similar, not exactly the same, issue reported, <a href="https://developer.apple.com/forums/thread/682420" rel="noreferrer">https://developer.apple.com/forums/thread/682420</a>. And I tried <code>standardAppearance</code> but this is not the solution since with <code>appearance</code> I can't change <code>tabBar.tintColor</code>.</p>