不多說(shuō)了，上代碼：
navigationBar 設(shè)置如下：

if #available(iOS 15, *) {
     let appearance = UINavigationBarAppearance()
     appearance.configureWithOpaqueBackground()
     appearance.backgroundImage = UIImage(named: "navigation-back-img")
     appearance.shadowImage = UIImage()
     appearance.shadowColor = UIColor.clear
     appearance.titleTextAttributes = [NSAttributedString.Key.font:UIFont.systemFont(ofSize: 18),NSAttributedString.Key.foregroundColor:k_FFFFFF]
     navigationBar.standardAppearance = appearance
     navigationBar.scrollEdgeAppearance = navigationBar.standardAppearance
}

UITabBar設(shè)置如下：

if #available(iOS 15, *) {
     let appearance = UITabBarAppearance()
     appearance.configureWithOpaqueBackground()
     appearance.backgroundColor = k_FAFAFA
     UITabBar.appearance().standardAppearance = appearance
     UITabBar.appearance().scrollEdgeAppearance = UITabBar.appearance().standardAppearance
}

原文來(lái)自蘋(píng)果開(kāi)發(fā)者社區(qū)：https://developer.apple.com/forums/thread/682420