Showing 'UIActivityViewController' in SwiftUI

Question

I want to let the user to be able to share a location but I don't know how to show UIActivityViewController in SwiftUI.

Answer 1

The basic implementation of UIActivityViewController in SwiftUI is

import UIKit
import SwiftUI

struct ActivityViewController: UIViewControllerRepresentable {

    var activityItems: [Any]
    var applicationActivities: [UIActivity]? = nil

    func makeUIViewController(context: UIViewControllerRepresentableContext<ActivityViewController>) -> UIActivityViewController {
        let controller = UIActivityViewController(activityItems: activityItems, applicationActivities: applicationActivities)
        return controller
    }

    func updateUIViewController(_ uiViewController: UIActivityViewController, context: UIViewControllerRepresentableContext<ActivityViewController>) {}

}

And here is how to use it.

struct MyView: View {

    @State private var isSharePresented: Bool = false

    var body: some View {
        Button("Share app") {
            self.isSharePresented = true
        }
        .sheet(isPresented: $isSharePresented, onDismiss: {
            print("Dismiss")
        }, content: {
            ActivityViewController(activityItems: [URL(string: "https://www.apple.com")!])
        })
    }
}

Answer 2

Based on Tikhonov's, the following code added a fix to make sure the activity sheet is dismissed properly (if not subsequently the sheet will not be presented).

struct ActivityViewController: UIViewControllerRepresentable {

    var activityItems: [Any]
    var applicationActivities: [UIActivity]? = nil
    @Environment(\.presentationMode) var presentationMode

    func makeUIViewController(context: UIViewControllerRepresentableContext<ActivityViewController>) -> UIActivityViewController {
        let controller = UIActivityViewController(activityItems: activityItems, applicationActivities: applicationActivities)
        controller.completionWithItemsHandler = { (activityType, completed, returnedItems, error) in
            self.presentationMode.wrappedValue.dismiss()
        }
        return controller
    }

    func updateUIViewController(_ uiViewController: UIActivityViewController, context: UIViewControllerRepresentableContext<ActivityViewController>) {}

}

Answer 3

It's a one time thing currently. .sheet will show it as a sheet, but bringing it up again from the same view will have stale data. Those subsequent shows of the sheet will also not trigger any completion handlers. Basically, makeUIViewController is called only once which is the only way to get the data to share into the UIActivityViewController. updateUIViewController has no way to update the data in your activityItems or reset the controller because those are not visible from an instance of UIActivityViewController.

Note that it doesn't work with UIActivityItemSource or UIActivityItemProvider either. Using those is even worse. The placeholder value doesn't show.

I hacked around some more and decided that maybe the problem with my solution was a sheet that was presenting another sheet, and when one went away then the other stayed.

This indirect way of having a ViewController do the presentation when it appears made it work for me.

class UIActivityViewControllerHost: UIViewController {
    var message = ""
    var completionWithItemsHandler: UIActivityViewController.CompletionWithItemsHandler? = nil

    override func viewDidAppear(_ animated: Bool) {
        share()
    }

    func share() {
        // set up activity view controller
        let textToShare = [ message ]
        let activityViewController = UIActivityViewController(activityItems: textToShare, applicationActivities: nil)

        activityViewController.completionWithItemsHandler = completionWithItemsHandler
        activityViewController.popoverPresentationController?.sourceView = self.view // so that iPads won't crash

        // present the view controller
        self.present(activityViewController, animated: true, completion: nil)
    }
}

struct ActivityViewController: UIViewControllerRepresentable {
    @Binding var text: String
    @Binding var showing: Bool

    func makeUIViewController(context: Context) -> UIActivityViewControllerHost {
        // Create the host and setup the conditions for destroying it
        let result = UIActivityViewControllerHost()

        result.completionWithItemsHandler = { (activityType, completed, returnedItems, error) in
            // To indicate to the hosting view this should be "dismissed"
            self.showing = false
        }

        return result
    }

    func updateUIViewController(_ uiViewController: UIActivityViewControllerHost, context: Context) {
        // Update the text in the hosting controller
        uiViewController.message = text
    }

}

struct ContentView: View {
    @State private var showSheet = false
    @State private var message = "a message"

    var body: some View {
        VStack {
            TextField("what to share", text: $message)

            Button("Hello World") {
                self.showSheet = true
            }

            if showSheet {
                ActivityViewController(text: $message, showing: $showSheet)
                    .frame(width: 0, height: 0)
            }

            Spacer()
        }
        .padding()
    }
}