我已经编写了一个代码，用于在 Xamarin IOS 中预览 PDF 文件。 现在我如何使用这个 QuickLook 框架在 Xamarin IOS 中注释这个 PDF ？

Question

UIViewController currentController = UIApplication.SharedApplication.KeyWindow.RootViewController;
while (currentController.PresentedViewController != null)
    currentController = currentController.PresentedViewController;
UIView currentView = currentController.View;
QLPreviewController preview = new QLPreviewController();
QLPreviewItem item = new QLPreviewItemBundle(fileData.FileName, fileData.FilePath);
preview.DataSource = new PreviewControllerDS(item);

currentController.PresentViewController(preview, true, null);

Answer 1

首先，创建一个继承自 QLPreviewControllerDataSource 的QLPreviewControllerDataSource 。

public class QuickLookSource : QLPreviewControllerDataSource
{
    List documents;

    public QuickLookSource(List docs)
    {
        documents = docs;
    }

    public override nint PreviewItemCount(QLPreviewController controller)
    {
        return documents.Count;
    }

    public override IQLPreviewItem GetPreviewItem(QLPreviewController controller, nint index)
    {
        return new PreviewItem(documents[(int)index]);
    }
}

public class PreviewItem : QLPreviewItem
{
    NSUrl fileUrl;

    public override NSUrl ItemUrl => fileUrl;
    public override string ItemTitle => fileUrl.LastPathComponent;

    public PreviewItem(string url)
    {
        fileUrl = NSUrl.FromFilename(url);
    }
}

然后呈现预览，创建一个新的QLPreviewController并将DataSource设置为您的数据源 class。 由于 controller 可以预览多个文件，请确保在导航到 controller 之前设置CurrentPreviewItemIndex ：

var previewController = new QLPreviewController();
previewController.DataSource = new QuickLookSource(source.Documents);

previewController.CurrentPreviewItemIndex = indexPath.Row;
NavigationController.PushViewController(previewController, true);

// You can present modally instead
// PresentViewController(previewController, true, null);