Fundo translúcido para a View Controller primária

TranslucentBackground.swift

func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {

    let splitViewController = window!.rootViewController as! UISplitViewController
    let navigationController = splitViewController.viewControllers[splitViewController.viewControllers.count-1] as! UINavigationController
    navigationController.topViewController!.navigationItem.leftBarButtonItem = splitViewController.displayModeButtonItem
    
    // Add a translucent background to the primary view controller.
    splitViewController.primaryBackgroundStyle = .sidebar
    
    splitViewController.delegate = self
    
    return true
}