ios – UISplitViewController all the time reveals the secondary view controller

I’ve an issue with UISplitViewController which is that this class all the time reveals the main points vc or secondary view controller as a substitute of major. Within the major vc I added

override func viewDidLoad() {
tremendous.viewDidLoad()

splitViewController?.delegate = self

//'allVisible' was deprecated in iOS 14.0: renamed to 'UISplitViewController.DisplayMode.oneBesideSecondary'

splitViewController?.preferredDisplayMode = .oneBesideSecondary

}

func splitViewController(_ splitViewController: UISplitViewController, collapseSecondary secondaryViewController: UIViewController, onto primaryViewController: UIViewController) -> Bool {
    return true
}

however nonetheless once I run the app the main points is seen first!