试图呈现视图不在窗口层次结构中的Xamarin_Forms_Platform_iOS_NavigationRenderer。

Question

你好，伙计们，我得到了这个问题：试图呈现在其视图不在窗口层次结构！有人知道如何创建一个UINavigationController打开一个PDF文件在iOSI创建Android和iOS的Dependecy服务，但只有在Android和iOS的工作somethings的PDF出现和somethings不我试图寻找一种方法来实现与UIViewController，但不工作这是类

public class SaveFile : ISaveFile
{

    public async Task<string> SaveFiles(string filename, byte[] bytes)
    {

        try
        {
            var documentsPath = System.Environment.GetFolderPath(System.Environment.SpecialFolder.MyDocuments);
            var filePath = Path.Combine(documentsPath, filename);

            File.WriteAllBytes(filePath, bytes);
            OpenPDF(filePath);
            //OpenFile(filePath);
            return filePath;
        }
        catch(Exception ex)
        {
            Debug.WriteLine("Error" + ex.Message + ex.StackTrace);
            return "";
        }
    }

    public  void OpenPDF(string filePath)
    {
          FileInfo fi = new FileInfo(filePath);

        QLPreviewController previewController = new QLPreviewController();


        previewController.DataSource = new PDFPreviewControllerDataSource(fi.FullName, fi.Name);

        //UIView uIView = previewController.View;
             UINavigationController controller = FindNavigationController();
        controller.ModalPresentationStyle = UIModalPresentationStyle.FullScreen;
        if (controller != null)

                  controller.PresentViewController(previewController, true,null);


    }

    /*
    public void OpenFile(string filePath)
    {
        var viewer = UIDocumentInteractionController.FromUrl(NSUrl.FromFilename(filePath));
        var controller = GetVisibleViewController();
        viewer.PresentOpenInMenu(controller.View.Frame, controller.View, true);
    }




    //*/

    private UINavigationController FindNavigationController()
    {
        foreach (var window in UIApplication.SharedApplication.Windows)
        {
            if (window.RootViewController.NavigationController != null)
                return window.RootViewController.NavigationController;
            else
            {
                UINavigationController val = CheckSubs(window.RootViewController.ChildViewControllers);
                if (val != null)
                    return val;
            }
        }

        return null;
    }

    private UINavigationController CheckSubs(UIViewController[] controllers)
    {
        foreach (var controller in controllers)
        {
            if (controller.NavigationController != null)
                return controller.NavigationController;
            else
            {
                UINavigationController val = CheckSubs(controller.ChildViewControllers);
                if (val != null)
                    return val;
            }
        }
        return null;
    }



    public class PDFItem : QLPreviewItem
    {
        string title;
        string uri;

        public PDFItem(string title, string uri)
        {
            this.title = title;
            this.uri = uri;
        }

        public override string ItemTitle
        {
            get { return title; }
        }

        public override NSUrl ItemUrl
        {
            get { return NSUrl.FromFilename(uri); }
        }


    }

    public class PDFPreviewControllerDataSource : QLPreviewControllerDataSource
    {
        string url = "";
        string filename = "";

        public PDFPreviewControllerDataSource(string url, string filename)
        {
            this.url = url;
            this.filename = filename;
        }

        public override IQLPreviewItem GetPreviewItem(QLPreviewController controller, nint index)
        {
            return (IQLPreviewItem)new PDFItem(filename, url);
        }

        public override nint PreviewItemCount(QLPreviewController controller)
        {
            return 1;
        }


    }
}

Answer 1

你可以检查 本回答 以了解您收到的错误信息。

解决方案:

移除find FindNavigationController 方法和用途 UIApplication.SharedApplication.KeyWindow.RootViewController.PresentViewController 递交 QLPreviewController :

   public void OpenPDF(string filePath)
    {
        FileInfo fi = new FileInfo(filePath);

        QLPreviewController previewController = new QLPreviewController();


        previewController.DataSource = new PDFPreviewControllerDataSource(fi.FullName, fi.Name);

        UIApplication.SharedApplication.KeyWindow.RootViewController.PresentViewController(previewController, true, null);


        //UIView uIView = previewController.View;
        //UINavigationController controller = FindNavigationController();
        //controller.ModalPresentationStyle = UIModalPresentationStyle.FullScreen;
        //if (controller != null)

        //    controller.PresentViewController(previewController, true, null);


    }

另外，你也可以使用webview来加载pdf文件。