如何让脚本上的UISplitViewController首先显示主视图?

为了使主视图在默认情况下在iPhone上折叠,请重写某些委托方法:

class SplitViewController : UISplitViewController {
    override func viewDidLoad() {
        super.viewDidLoad()
        self.delegate = self
    }
}

extension SplitViewController : UISplitViewControllerDelegate {

    // The default for this is .secondary!!
    @available(iOS 14.0, *)
    public func splitViewController(_ svc: UISplitViewController, 
        topColumnForCollapsingToProposedTopColumn 
        proposedTopColumn: UISplitViewController.Column) -> UISplitViewController.Column {
        return .primary
    }

    // default is false!
    public func splitViewController(_ splitViewController: UISplitViewController,
                             collapseSecondary secondaryViewController:UIViewController,
                             onto primaryViewController:UIViewController) -> Bool {
        return true
    }
}

以前你会用 preferredDisplayMode = .primaryOverlay