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当用户在我的新闻聚合器中发送文章链接时，我正在尝试自定义链接预览，该聚合器内置在 SwiftUI 中。

我正在使用从发布者的网站获取缩略图图像LPMetadataProvider，然后使用该图像创建我自己的LPLinkMetadata对象以及我提供的其他元数据。即“显示纽约时报的文章图像缩略图，但当用户在他们的消息应用程序中点击链接预览时，将用户深层链接到我的应用程序中的文章”。

我可以提供没有图像的预览，它可以深层链接到我的应用程序，或者图像本身，没有深层链接。我怎样才能得到两者？

public class LinkPresentationItemSource: NSObject, UIActivityItemSource {

    public var metadata: LPLinkMetadata?
    public var articleID: String
    public var title: String
    public var imageUrl: String

    enum Constant {
        static let deepLinkURLSchemeAndHost = "https://www.somedeeplinkurl.com/"
    }

    private func createDeepLinkURLFrom(id: String?) -> String {
        guard let selectedArticleID = id else {
            return ""
        }
        return Constant.deepLinkURLSchemeAndHost + selectedArticleID
    }

    // Prepare data to share
    public func activityViewControllerLinkMetadata(
        _ activityViewController: UIActivityViewController) -> LPLinkMetadata? {

            let lpLinkMetadataProvider = LPMetadataProvider()
            let lpLinkMetadata = LPLinkMetadata()

            guard let imageUrl = URL(string: imageUrl) else {
                return nil
            }
            lpLinkMetadataProvider.startFetchingMetadata(for: imageUrl) { metadata, _ in
                guard let metadata = metadata else {
                    return
                }
                DispatchQueue.main.async {
                    lpLinkMetadata.imageProvider = NSItemProvider(contentsOf: metadata.url)
                }
            }

            guard let originalURL = URL(string: createDeepLinkURLFrom(id: articleID)) else {
                return nil
            }
            lpLinkMetadata.originalURL = originalURL
            lpLinkMetadata.url = lpLinkMetadata.originalURL
            lpLinkMetadata.title = title

            metadata = lpLinkMetadata

            return lpLinkMetadata
    }

    // Placeholder for real data, we don't care in this example so just return a simple string
    public func activityViewControllerPlaceholderItem(_ activityViewController: UIActivityViewController) -> Any {
        return "Placeholder"
    }

    /// Return the data will be shared
    /// - Parameters:
    ///   - activityType: Ex: mail, message, airdrop, etc..
    public func activityViewController(_ activityViewController: UIActivityViewController,
                                       itemForActivityType activityType: UIActivity.ActivityType?) -> Any? {
        guard let metadata = metadata else {
            return nil
        }

        return metadata.url
    }

    public init(articleID: String, imageUrl: String, title: String) {
        self.articleID = articleID
        self.imageUrl = imageUrl
        self.title = title
    }
}

具体来说，以下方法中返回的内容似乎不包括我提供的所有元数据。如果我返回metadata或LPLinkPreview(metadata: metadata)消息应用程序根本没有填充任何链接预览：

public func activityViewController(_ activityViewController: UIActivityViewController,
                                       itemForActivityType activityType: UIActivity.ActivityType?) -> Any?
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