ios - 向 Storyboard添加了 UIViewController，但无法在 xamarin ios 中以编程方式读取它

Question

我在 Storyboard中添加了一个 UIViewController 并尝试访问它并将其显示出来，按照下面编写的代码。但由于某些原因，它被读取为 NULL。 虽然这段代码运行良好。我调试了它们，我得到了 wcv 的 null 值，并得到了 acv 的值，是的。如果我检查 Storyboard 文件的 xml 代码，我可以找到 View Controller ，其 ID 为 StoyboardId 和 RestorationId

注意: 相同的导航代码适用于其他地方。我正在使用 Xamarin-iOS(独立许可证)

WelcomeScreenController2 wcv =(UIApplication.SharedApplication.Delegate as AppDelegate).StoryBoard.InstantiateViewController ("WelcomeScreenController2") as WelcomeScreenController2;
                                        this.NavigationController.PushViewController(wcv,true);




ActivityViewController2 acv = (UIApplication.SharedApplication.Delegate as AppDelegate).StoryBoard.InstantiateViewController ("ActivityViewController2") as ActivityViewController2;
                                        this.NavigationController.PushViewController (acv, true);

两者的区别在于，ActivityViewController2继承了BaseController，而WelcomeScreenController2继承了UIViewController

BaseController代码

public partial class BaseController : UIViewController
    {
        // provide access to the sidebar controller to all inheriting controllers
        protected SidebarController SidebarController { 
            get {
                return (UIApplication.SharedApplication.Delegate as AppDelegate).RootViewController.SidebarController;
            } 
        }

        // provide access to the sidebar controller to all inheriting controllers
        protected NavController  NavController { 
            get {
                return (UIApplication.SharedApplication.Delegate as AppDelegate).RootViewController.NavController;
            } 
        }

        public BaseController (IntPtr handle) : base (handle)
        {
        }
        public BaseController(string nibName, NSBundle bundle) : base(nibName, bundle)
        {
        }



        public override void ViewDidLoad()
        {
            base.ViewDidLoad();

            NavigationItem.SetLeftBarButtonItem(
                new UIBarButtonItem(UIImage.FromBundle("menu-icon")
                    , UIBarButtonItemStyle.Plain
                    , (sender,args) => {
                        SidebarController.ToggleMenu();
                    }), true);
        }

        public override void ViewWillAppear (bool animated)
        {   
            base.ViewWillAppear (animated);

        }

        public override void ViewDidAppear (bool animated)
        {
            base.ViewDidAppear (animated);
        }

        public override void ViewWillDisappear (bool animated)
        {
            base.ViewWillDisappear (animated);
        }

        public override void ViewDidDisappear (bool animated)
        {
            base.ViewDidDisappear (animated);
        }

    }

Storyboard代码 SS

WelcomeScreenController2 的 StoryBoard 代码

<scene sceneID="684">
            <objects>
                <viewController id="685" sceneMemberID="viewController" customClass="WelcomeScreenController2" storyboardIdentifier="WelcomeScreenController2" restorationIdentifier="WelcomeScreenController2">
                    <view key="view" contentMode="scaleToFill" id="686">
                        <rect key="frame" x="0.0" y="0.0" width="320" height="568"/>
                        <autoresizingMask key="autoresizingMask" flexibleMaxX="YES" flexibleMaxY="YES"/>
                        <color key="backgroundColor" white="1" alpha="1" colorSpace="custom" customColorSpace="calibratedWhite"/>
                    </view>
                </viewController>
                <placeholder placeholderIdentifier="IBFirstResponder" id="687" userLabel="First Responder" sceneMemberID="firstResponder"/>
            </objects>
            <point key="canvasLocation" x="4000" y="135"/>
        </scene>

WelcomeScreen2 类

public partial class WelcomeScreenController2 : UIViewController
    {
        public WelcomeScreenController2 (IntPtr handle) : base (handle)
        {
        }
}

ActivityViewController2 类

public partial class ActivityViewController2 : BaseController
    {
public ActivityViewController2 (IntPtr handle) : base (handle)
        {
            Title = "ACTIVITY";
        }

        public ActivityViewController2 () : base ((string)null, null)
        {
            Title = "ACTIVITY";
        }
}

Answer 1

它不需要我改变任何东西。只需清洁解决方案并再次调试/运行，这对我有用。

但正如@Dimitris 在评论中所写，这可能是选角问题。那为什么我确切地说它是新的 UIViewController 而不是旧的，清理与它有什么关系，直到清理后它运行良好？