自作iOSアプリからmixi2アプリに画像を共有する際の実装ポイント

extension UIActivity.ActivityType {
    static let mixi = UIActivity.ActivityType(rawValue: "jp.co.mixi.mercury.ShareExtension")
}

import LinkPresentation
import UIKit
import UniformTypeIdentifiers

final class ImageFileActivityItem: NSObject, UIActivityItemSource {
    let fileUrl: URL
    let fileName: String
    let image: UIImage?

    init(fileUrl: URL, image: UIImage?) {
        self.fileUrl = fileUrl
        self.image = image
        self.fileName = fileUrl.lastPathComponent
    }

    func activityViewControllerPlaceholderItem(_: UIActivityViewController) -> Any {
        image ?? UIImage()
    }

    func activityViewController(_: UIActivityViewController, itemForActivityType activityType: UIActivity.ActivityType?) -> Any? {
        return switch activityType {
        case .mixi:
            image
        default:
            fileUrl
        }
    }

    func activityViewController(_: UIActivityViewController, subjectForActivityType _: UIActivity.ActivityType?) -> String {
        fileName
    }

    func activityViewController(_: UIActivityViewController, dataTypeIdentifierForActivityType _: UIActivity.ActivityType?) -> String {
        UTType.image.identifier
    }

    func activityViewControllerLinkMetadata(_: UIActivityViewController) -> LPLinkMetadata? {
        guard let image = image else { return nil }

        let metadata = LPLinkMetadata()
        metadata.title = fileName
        metadata.imageProvider = NSItemProvider(object: image)
        return metadata
    }
}