SwiftUI View → UIImage Snapshot + Share Sheet
==============================================

Renders any SwiftUI view into a UIImage, then presents the system share sheet
with the image and accompanying text.

Usage:

    func share() {
        let image = MyShareView()
            .frame(width: 380, height: 370)
            .snapshot

        let text = """
        Check out this coin on MyApp.
        Download for free: https://example.com
        """

        let activityItemSource = ActivityControllerItemSource(title: "MyApp", text: text)
        let activityViewController = UIActivityViewController(
            activityItems: [image, activityItemSource],
            applicationActivities: nil
        )

        // Required for iPad — present as popover
        if let popover = activityViewController.popoverPresentationController,
           let rootView = UIApplication.shared.window?.rootViewController?.view {
            popover.sourceView = rootView
            popover.sourceRect = .zero
            popover.permittedArrowDirections = []
        }

        UIApplication.shared.window?.rootViewController?.present(
            activityViewController,
            animated: true
        )
    }


Snapshot extension:

import SwiftUI
import UIKit

extension View {
#if os(iOS)
    var snapshot: UIImage {
        let controller = UIHostingController(rootView: self)
        let view = controller.view

        let targetSize = controller.view.intrinsicContentSize
        view?.bounds = CGRect(origin: .zero, size: targetSize)
        view?.backgroundColor = Color.surface.uiColor

        let renderer = UIGraphicsImageRenderer(size: targetSize)

        return renderer.image { _ in
            view?.drawHierarchy(in: controller.view.bounds, afterScreenUpdates: true)
        }
    }
#endif
}


ActivityControllerItemSource (custom share text + link preview metadata):

import UIKit
import LinkPresentation

class ActivityControllerItemSource: NSObject, UIActivityItemSource {
    var title: String
    var text: String

    init(title: String, text: String) {
        self.title = title
        self.text = text
        super.init()
    }

    func activityViewControllerPlaceholderItem(_ activityViewController: UIActivityViewController) -> Any {
        return text
    }

    func activityViewController(_ activityViewController: UIActivityViewController, itemForActivityType activityType: UIActivity.ActivityType?) -> Any? {
        return text
    }

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

    func activityViewControllerLinkMetadata(_ activityViewController: UIActivityViewController) -> LPLinkMetadata? {
        let appIcon = UIImage(named: "AppIconRaw")
        let metadata = LPLinkMetadata()
        metadata.title = title
        metadata.iconProvider = NSItemProvider(object: appIcon ?? UIImage())
        metadata.originalURL = URL(fileURLWithPath: text)
        return metadata
    }
}


Notes:
- Set an explicit .frame() on the view before calling .snapshot so intrinsicContentSize is correct.
- Uses drawHierarchy(afterScreenUpdates: true) so async layout (images, etc.) has time to render.
- `ActivityControllerItemSource` lets you attach a title, body text, and app icon to the share sheet preview.
- On iPad, UIActivityViewController must be presented as a popover or it will crash.