I have an application that is meant to be a "watch together" GroupActivity using SharePlay that coordinates video playback using AVPlayerPlaybackCoordinator. In the current implementation, the activity begins before opening the AVPlayer, however when clicking the back button within the AVPlayer view, the user is prompted to "End Activity for Everyone" or "End Activity for just me". There is not an option to continue the group activity. My goal is to retain the same GroupSession, even if a user exits the AVPlayer view. Is there a way to avoid ending the session when coordinating playback using the AVPlayerPlaybackCoordinator? private func startObservingSessions() async { sessionInfo = .init() // Await new sessions to watch video together. for await session in MyActivity.sessions() { // Clean up the old session, if it exists. cleanUpSession(groupSession) #if os(visionOS) // Retrieve the new session's system coordinator object to update its configuration. guard let systemCoordinator = await session.systemCoordinator else { continue } // Create a new configuration that enables all participants to share the same immersive space. var configuration = SystemCoordinator.Configuration() // Sets up spatial persona configuration configuration.spatialTemplatePreference = .sideBySide configuration.supportsGroupImmersiveSpace = true // Update the coordinator's configuration. systemCoordinator.configuration = configuration #endif // Set the app's active group session before joining. groupSession = session // Store session for use in sending messages sessionInfo?.session = session let stateListener = Task { await self.handleStateChanges(groupSession: session) } subscriptions.insert(.init { stateListener.cancel() }) // Observe when the local user or a remote participant changes the activity on the GroupSession let activityListener = Task { await self.handleActivityChanges(groupSession: session) } subscriptions.insert(.init { activityListener.cancel() }) // Join the session to participate in playback coordination. session.join() } } /// An implementation of `AVPlayerPlaybackCoordinatorDelegate` that determines how /// the playback coordinator identifies local and remote media. private class CoordinatorDelegate: NSObject, AVPlayerPlaybackCoordinatorDelegate { var video: Video? // Adopting this delegate method is required when playing local media, // or any time you need a custom strategy for identifying media. Without // implementing this method, coordinated playback won't function correctly. func playbackCoordinator(_ coordinator: AVPlayerPlaybackCoordinator, identifierFor playerItem: AVPlayerItem) -> String { // Return the video id as the player item identifier. "\(video?.id ?? -1)" } } /// /// Initializes the playback coordinator for synchronizing video playback func initPlaybackCoordinator(playbackCoordinator: AVPlayerPlaybackCoordinator) async { self.playbackCoordinator = playbackCoordinator if let coordinator = self.playbackCoordinator { coordinator.delegate = coordinatorDelegate } if let activeSession = groupSession { // Set the group session on the AVPlayer instances's playback coordinator // so it can synchronize playback with other devices. playbackCoordinator.coordinateWithSession(activeSession) } } /// A coordinator that acts as the player view controller's delegate object. final class PlayerViewControllerDelegate: NSObject, AVPlayerViewControllerDelegate { let player: PlayerModel init(player: PlayerModel) { self.player = player } #if os(visionOS) // The app adopts this method to reset the state of the player model when a user // taps the back button in the visionOS player UI. func playerViewController(_ playerViewController: AVPlayerViewController, willEndFullScreenPresentationWithAnimationCoordinator coordinator: UIViewControllerTransitionCoordinator) { Task { @MainActor in // Calling reset dismisses the full-window player. player.reset() } } #endif }

Platform and Version Development Environment: Xcode 16 Beta 3 visionOS 2 Beta 3 Description of Problem I am currently working on integrating SharePlay into my visionOS 2 application. The application features a fully immersive space where users can interact. However, I have encountered an issue during testing on TestFlight. When a user taps a button to activate SharePlay via the GroupActivity's activate() method within the immersive space, the immersive space visually disappears but is not properly dismissed. Instead, the immersive space can be made to reappear by turning the Digital Crown. Unfortunately, when it reappears, it overlaps with the built-in OS immersive space, resulting in a mixed and confusing user interface. This behavior is particularly concerning because the immersive space is not progressive and should not work with the Digital Crown being turned. It is important to note that this problem is only present when testing the app via TestFlight. When the same build is compiled with the Release configuration and run directly through Xcode, the immersive space behaves as expected, and the issue does not occur. Steps to Reproduce Build a project that includes a fully immersive space and incorporates GroupActivity support. Add a button within a window or through a RealityView attachment that triggers the GroupActivity's activate() method. Upload the build to TestFlight. Connect to a FaceTime call. Open the app and enter a immersive space then press the button to activate the Group Activity.

Hi all, Currently working on a shareplay feature where users pull data from a remote source and are able to share it in a volumetric window with others in the facetime call. However, I am running into an issue where the group activity/session seems to be throwing an error on the recipient of the journal's attachment with the description of notSupported. As I understand it, we use GroupSessionJournal for larger pieces of data like images (like in the Drawing Together example) and in my case 3d models. The current flow goes as follows: User will launch the app and fetch a model from remote. User can start a shareplay instance in which the system captures the volumetric window for users to join and see. At this point, only the original user can see the model. The user can press a button to share this model with the other participants using /// modelData is serialized `Data` try await journal.add(modelData) In the group session configuration, I already have a task listening for for await attachments in journal.attachments { for attachment in attachments { ... } } This task attempts to load data via the following code: let modelData = try await attachment.load(Data.self) /// this is where the error is thrown: `notSupported` I expect the attachment.load(Data.self) call to properly deliver the model data, but instead I am receiving this error. I have also attempted to wrap the model data within an enclosing struct that has a name and data property and conform the enclosing struct to Transferable but that continued to throw the notSupported error. Is there something I'm doing wrong or is this simply a bug in the GroupSessionJournal? Please let me know if more information is required for debugging and resolution. Thanks!

I learned Sharplay from the WWDC video. I understand the creation of seats, but I can't learn some of the following contents well, so I hope you can help me. The content is as follows: I have set up the seats. struct TeamSelectionTemplate: SpatialTemplate { let elements: [any SpatialTemplateElement] = [ .seat(position: .app.offsetBy(x: 0, z: 4)), .seat(position: .app.offsetBy(x: 1, z: 4)), .seat(position: .app.offsetBy(x: -1, z: 4)), .seat(position: .app.offsetBy(x: 2, z: 4)), .seat(position: .app.offsetBy(x: -2, z: 4)), ] } It was mentioned in one of my previous posts: "I hope you can give me a SharePlay Button. After pressing it, it will assign all users in Facetime to a seat with elements quantified in TeamSe lectionTemplate.", and someone replied to me and asked me to try systemCoordinator.configuration.spatialTemplatePreference = .custom (TeamSelectionTemplate()), however, Xcode error Cannot find 'systemCoordinator' in scope How to solve it? Thank you!

Hello, currently working on a shareplay feature that allows users to pull 3d models from icloud and view it via volumes/immersive space on the vision pro. Was able to get the sharing working with multiple windows recently so now all that's left is to be able to sync/share the model in the SharePlay session. As I understand it, we should generally use GroupSessionMessenger for commands and light data like model positioning/syncing properties. Whereas for bigger pieces of data (images/videos/models), we should send these through GroupSessionJournal which the group session manages and syncs it for all users in the call. I have a button to get the current user's model data and add it to the journal via /// modelData is type `Data` try await journal.add(modelData) I have also set up a task to observe/receive updates to the journal's attachments in when receiving a group session. for await groupSession in MyModelActivity.sessions() { ... tasks.insert { Task { for await attachments in journal.attachments { for attachment in attachments { do { let modelData = try await attachment.load(Data.self) // throws error here - `notSupported` let modelUrl = writeModelDataToTempDirectory(modelData: modelData) self.modelUrlToLoadForGroupSession = modelUrl } catch let error { print("Error: \(error)") } } } } } } Not quite sure why I'm running into an error being thrown when attempting to load the attachment data on the other devices, any thoughts? The documentation for add(_:) and load(_:) say that the attachment should conform to Transferable but Data.Type should already conform to Transferable

Hi all, I had previously posted this on the Media Technologies section but didn't receive any replies so thought I would try my luck here. Apologies if re-posting questions on the forum in a short-ish time span is against the rules, but would greatly appreciate some assistance with the following situation regarding GroupSessionJournal and loading attachments. I'm currently working on a shareplay feature that allows users to pull 3d models from icloud and view it via volumes/immersive space on the vision pro. Was able to get the sharing working with multiple windows recently so now all that's left is to be able to sync/share the model in the SharePlay session. As I understand it, we should generally use GroupSessionMessenger for commands and light data like model positioning/syncing properties. Whereas for bigger pieces of data (images/videos/models), we should send these through GroupSessionJournal which the group session manages and syncs it for all users in the call. I have a button to get the current user's model data and add it to the journal via /// modelData is type `Data` try await journal.add(modelData) I have also set up a task to observe/receive updates to the journal's attachments in when receiving a group session. for await groupSession in MyModelActivity.sessions() { ... tasks.insert { Task { for await attachments in journal.attachments { for attachment in attachments { do { let modelData = try await attachment.load(Data.self) // throws error here - `notSupported` let modelUrl = writeModelDataToTempDirectory(modelData: modelData) self.modelUrlToLoadForGroupSession = modelUrl } catch let error { print("Error: \(error)") } } } } } } Not quite sure why I'm running into an error being thrown when attempting to load the attachment data on the other devices, any thoughts? The documentation for add(_:) and load(_:) say that the attachment should conform to Transferable but Data.Type should already conform to Transferable

I followed the WWDC video to learn Sharplay. I understood the first creation of seats, but I couldn't learn some of the following content very well, so I hope you can give me a list code. The contents are as follows: I have already taken a seat. struct TeamSelectionTemplate: SpatialTemplate { let elements: [any SpatialTemplateElement] = [ .seat(position: .app.offsetBy(x: 0, z: 4)), .seat(position: .app.offsetBy(x: 1, z: 4)), .seat(position: .app.offsetBy(x: -1, z: 4)), .seat(position: .app.offsetBy(x: 2, z: 4)), .seat(position: .app.offsetBy(x: -2, z: 4)), ] } I hope you can give me a SharePlay Button. After pressing it, it will assign all users in Facetime to a seat with elements quantified in TeamSelectionTemplate. Thank you very much.

How to display the user's own persona in a view

Hi all, been working with visionOS for a bit so far and am trying to develop a feature that allows users to shareplay and interact with a 3D model pulled from the cloud (icloud in this case, but may use a regular backend service in the future). Ideally, I would want to be able to click a custom button on a regular window that starts the group activity/shareplay with another person in the facetime call and opens the volumetric window with the model and can switch to an immersive space freely. TLDR/questions at the very end for reference point. I was able to get this working when only working with a single window group (i.e. a volumetric window group scene and an immersive space scene). However I am running into trouble getting shareplay to correctly grab the desired scene (or any scene at all) when I have multiple window group scenes defined. I have been referencing the following documentation in my attempts to implement this: https://developer.apple.com/documentation/groupactivities/sceneassociationbehavior https://developer.apple.com/documentation/groupactivities/adding-spatial-persona-support-to-an-activity https://developer.apple.com/documentation/groupactivities/defining-your-apps-shareplay-activities https://developer.apple.com/documentation/groupactivities/joining-and-managing-a-shared-activity No luck so far however. Additionally, here is a quick breakdown of what I've done so far to attempt implementation: Define group activity that contains static var activityIdentifier: String and var metadata: GroupActivityMetadata as well as conforms to GroupActivity. Provide methods to start shareplay via a startShareplay() method that instantiates the above group activity and switch awaits on activity.prepareForActivation() to activate the activity if case .activationPreferred. I have also provided a separate group activity registration method to start shareplay via airdrop as mentioned in the Building spatial SharePlay experiences developer video (timestamped), which does expose a group activity to the share context menu/ornament but does not indicate being shared afterwards. On app start, trigger a method to configure group sessions and provide listeners for sessions (including subscribers for active participants, session state, messages of the corresponding state type - in my case it's ModelState.self, journal attachments for potentially providing models that the other user may not have as we are getting models from cloud/backend, local participant states, etc). At the very end, call groupSession.join(). Add external activation handlers to the corresponding scenes in the scene declaration (as per this documentation on SceneAssociationBehavior using the handlesExternalEvents(matching:) scene modifier to open the scene when shareplay starts). I have also attempted using the view modifier handlesExternalEvents(preferring:allowing:) on views but also no luck. Both are being used with the corresponding activityIdentifier from the group activity and I've also tried passing a specific identifier while using the .content(_) sceneAssociationBehavior as well but no luck there either. I have noted that in this answer regarding shareplay in visionOS, the VP engineer notes that when the app receives the session, it should setup any necessary UI then join the session, but I would expect even if the UI isn't being set up via the other person's session that the person who started shareplay should still see the sharing ornament turn green on the corresponding window which doesn't seem to occur. In fact, none of the windows that are open even get the green sharing ornament (just keeps showing "Not shared"). TLDR: Added external events handling and standard group activity stuff to multi-window app. When using shareplay, no windows are indicated as being shared. My questions thus are: Am I incorrect in my usage of the scene/view modifiers for handlesExternalEvents to open and associate a specific windowgroup/scene with the group activity? In regards to opening a specific window when the group activity is activated, how do we pass any values if the window group requires it? i.e. if it's something like WindowGroup(id: ..., for: URL.self) { url in ... } Do I still need to provide UI setup in the session listener (for await session in MyActivity.sessions())? Is this just a simple openWindow? Past the initializing shareplay stuff above, what are the best practices for sharing 3d models that not all users in the session might have? Is it adding it as an attachment to GroupSessionJournal? Or should I pass the remote URL to everyone to download the model locally instead? Thanks for any help and apologies for the long post. Please let me know if there's any additional information I can provide to help resolve this.

I am trying to create demo for spatial meeting using persona also refer apple videos, But not getting clear idea about it. Any one could you please guide me step by step process or any code are appreciated for learning.

Hi! I'm working on trying to integrate SharePlay with Personas into a visionOS app. I'm still at the beginning stages and I'm following some of the 1st party documentation + videos from WWDC. https://developer.apple.com/videos/play/wwdc2023/10087 https://developer.apple.com/documentation/groupactivities/adding-spatial-persona-support-to-an-activity#Update-the-immersion-level-automatically-for-a-Full-Space I'm using: Xcode 15.3 (15E204a) visionOS 1.1 (21O209) In both the examples linked above, they reference systemCoordinator.groupImmersionStyle However this doesn't seem to exist. Also, it's not clear how to open/transition to the various spaces if groupImmersionStyle did exist and I could detect full, mixed, progressive spaces. Am I missing something? Was this removed or did I configure something incorrectly? Is there a full sample for SharePlay + visionOS somewhere that I might have missed? Thanks for any help!

I'd like to implement a fully immersive space that's experienced by multiple Vision Pro users simultaneously via SharePlay. To do this, the multiple Vision Pro users will join a SharePlay-enabled visionOS window that has a button to enter a fully immersive space, which is also SharePlay-enabled. I tried following the WWDC sessions and docs, but they don't provide enough detail about integrating SharePlay into an existing window and immersive space. How can I adjust my SharePlay code so it makes my visionOS window + fully immersive space SharePlay-able? Please see existing code below for a SharePlay visionOS widow, thank you. P.S. WWDC ref. https://developer.apple.com/videos/play/wwdc2023/10087 import SwiftUI import RealityKit import RealityKitContent import GroupActivities import LinkPresentation struct SharePlayWorld: View, GroupActivity { @Environment(ViewModel.self) private var model @Environment(\.openWindow) private var openWindow @Environment(\.dismissWindow) private var dismissWindow @Environment(\.openImmersiveSpace) private var openImmersiveSpace @Environment(\.dismissImmersiveSpace) private var dismissImmersiveSpace var body: some View { @Bindable var model = model Toggle( model.isShowingPracticeSpace ? "Leave Space" : "Enter Space", isOn: $model.isShowingPracticeSpace ) .onChange(of: model.isShowingPracticeSpace) { _, isShowing in Task { if isShowing { await openImmersiveSpace(id: "SharePlayWorld") } else { await dismissImmersiveSpace() } } } .toggleStyle(.button) } // SHAREPLAY CODE private func startSharePlaySession() async { for await session in SharePlayWorld.sessions() { guard let systemCoordinator = await session.systemCoordinator else { continue } let isLocalParticipantSpatial = systemCoordinator.localParticipantState.isSpatial Task.detached { for await localParticipantState in systemCoordinator.localParticipantStates { if localParticipantState.isSpatial { // Start syncing scroll position } else { // Stop syncing scroll position } } } var configuration = SystemCoordinator.Configuration() configuration.spatialTemplatePreference = .sideBySide systemCoordinator.configuration = configuration session.join() } // Create the activity let activity = SharePlayWorld() // Register the activity on the item provider let itemProvider = NSItemProvider() itemProvider.registerGroupActivity(activity) // Create the activity items configuration let configuration = await UIActivityItemsConfiguration(itemProviders: [itemProvider]) // Provide the metadata for the group activity configuration.metadataProvider = { key in guard key == .linkPresentationMetadata else { return nil } let metadata = LPLinkMetadata() metadata.title = "Explore Together" metadata.imageProvider = NSItemProvider(object: UIImage(named: "explore-activity")!) return metadata } self.activityItemsConfiguration = configuration } } #Preview { SharePlayWorld() .environment(ViewModel()) }

I built two parts of my app a bit disjointed: my physics component, which controls all SceneReconstruction, HandTracking, and WorldTracking. my spatial GroupActivities component that allows you to see personas of those that join the activity. My problem: When trying to use any DataProvider in a spatial experience, I get the ARKit Session Event: dataProviderStateChanged, which disables all of my providers. My question: Has anyone successfully been able to find a workaround for this? I think it would be amazing to have one user be able to be the "host" for the activity and the scene reconstruction provider still continue to run for them.

I am trying to present a GroupActivitySharingController using SwiftUI. I am using a NSViewControllerRepresentable: @State var event : Event func makeNSViewController(context: NSViewControllerRepresentableContext<MeetingGroupActivitySharingRepresentableView>) -> GroupActivitySharingController { return try! GroupActivitySharingController(MeetingGroupActivity(event: event)) } func updateNSViewController(_ nsViewController: GroupActivitySharingController , context: NSViewControllerRepresentableContext<MeetingGroupActivitySharingRepresentableView>) { print("Updating VC") } } I present it as following : .sheet(isPresented: $showGroupActivitySharingView) { MeetingGroupActivitySharingRepresentableView(event: observedEvent.event) } It works fine on iOS, however on MacOS, I cannot dismiss the view. I see the following error: dismissViewController:: Error: maybe this view controller was not presented? ( 0 CoreFoundation 0x000000019d75accc __exceptionPreprocess + 176 1 libobjc.A.dylib 0x000000019d242788 objc_exception_throw + 60 2 Foundation 0x000000019e8cbc6c -[NSCalendarDate initWithCoder:] + 0 3 AppKit 0x00000001a145a77c -[NSViewController dismissViewController:] + 224 4 _GroupActivities_AppKit 0x0000000232d65cf0 $s23_GroupActivities_AppKit0A25ActivitySharingControllerC011dismissViewG06resultyAA0aeF6ResultO_tFyyYaYbScMYccfU_TY0_ + 444 5 _GroupActivities_AppKit 0x0000000232d67b65 $s23_GroupActivities_AppKit0A25ActivitySharingControllerC011dismissViewG06resultyAA0aeF6ResultO_tFyyYaYbScMYccfU_TATQ0_ + 1 6 _GroupActivities_AppKit 0x0000000232d68bd9 $sIeghH_ytIeghHr_TRTQ0_ + 1 7 _GroupActivities_AppKit 0x0000000232d68bdd $sIeghH_ytIeghHr_TRTATQ0_ + 1 8 _GroupActivities_AppKit 0x0000000232d66931 $sxIeghHr_xs5Error_pIegHrzo_s8SendableRzs5NeverORs_r0_lTRyt_Tg5TQ0_ + 1 9 _GroupActivities_AppKit 0x0000000232d68ba5 $sxIeghHr_xs5Error_pIegHrzo_s8SendableRzs5NeverORs_r0_lTRyt_Tg5TATQ0_ + 1 10 libswift_Concurrency.dylib 0x0000000263cfb0f9 _ZL23completeTaskWithClosurePN5swift12AsyncContextEPNS_10SwiftErrorE + 1 ) Any idea what is going on?

I'm developing a motion tracking app that takes requires a real-time view of an iPhone camera to capture the person's body. The motion is mapped to a virtual body. Currently this appears overlayed on the person that the iPhone sees. However, I want to transmit this real time 3D virtual body to a different Apple device, as an AR app, that the other user can place in their environment. Any suggestions on how I can get this 3d model to be viewable by another user (and maintain live updating based on motion tracking)?

I am adding Group Activities integration with a MacCatalyst app. I have added the Group Activities entitlement in Xcode. I also checked the entitlements with : codesign --display --entitlements :- I can see the entitlement : <key>com.apple.developer.group-session</key><true/><key> The feature work fine on iPadOS but when I run it on MacOS, the GroupActivitySharingController is not loading properly. I get the following error messages: Cannot run query EXQuery: extension point com.apple.groupactivities platforms: 6 with error: (null) Failed to lookup extension with query EXQuery: extension point com.apple.groupactivities platforms: 6 on <_GroupActivities_UIKit.PeoplePickerController: 0x600005020980> Failed to fetch config for hostViewController <_GroupActivities_UIKit.PeoplePickerController: 0x600005020980> Failed to build remote hostViewController for <_GroupActivities_UIKit.GroupActivitySharingController: 0x1417f1250> Failed to fetch extensionViewController Calling -viewDidAppear: directly on a view controller is not supported, and may result in out-of-order callbacks and other inconsistent behavior. Use the -beginAppearanceTransition:animated: and -endAppearanceTransition APIs on UIViewController to manually drive appearance callbacks instead. Make a symbolic breakpoint at UIViewControllerAlertForAppearanceCallbackMisuse to catch this in the debugger. View controller: <_GroupActivities_UIKit.GroupActivitySharingController: 0x1417f1250> I got a similar error on iPadOS when the entitlement was not added. Now that I have the entitlement, the error appears only on MacOS. Does MacOS/MacCatalyst use a different entitlements file? What could be cuasing this?

I have copied an sqlite file from document to app group container. I found that if I delete the app and reinstall, the file is automatically created. How is that happed? The app group container is not just a folder and can be synchronized by iCloud? I cannot find any informations about the feature. If there is, please show me the link, thanks

Hello, I am new to Apple development and am wondering if I have configuration missing to enable access to FaceTime within the visionOS Simulator. I am on XCode 15.2, Simulator Version 15.2, and visionOS 1.0. I am trying to use the "Destinations Video" code as reference for implementing a shared activity but even running this in the simulator doesn't seem to prompt the SharePlay buttons shown in the video: https://developer.apple.com/documentation/visionos/destination-video I am trying to test out SharePlay and GroupActivities but am not sure where exactly to download the developer Persona specified in the release notes here and how to configure that: https://developer.apple.com/documentation/visionos-release-notes/visionos-release-notes#FaceTime Can someone advise on how to enable FaceTime + SharePlay in the visionOS Simulator?

Hi, I am having trouble with Share Play working. When I create and run the GroupActivity sample in SharePlay, I get the following message and GroupActivity does not work. https://mitemmetim.medium.com/shareplay-tutorial-share-custom-data-between-ios-and-macos-a50bfecf6e64 Dropping activity as there is no active conversation: <TUMutableConversationActivityCreateSessionRequest 0x2836731c0 activityIdentifier=jp.co.1planet.sample.SharePlayTutorial.SharePlayActivity applicationContext={length = 42, bytes = 0x62706c69 73743030 d0080000 00000000 ... 00000000 00000009 } metadata=<TUConversationActivityMetadata 0x28072d380 context=CPGroupActivityGenericContext title=SharePlay Example sceneAssociationBehavior=<TUConversationActivitySceneAssociationBehavior 0x28237a740 targetContentIdentifier=(null) shouldAssociateScene=1 preferredSceneSessionRole=(null)>> UUID=3137DDE4-F5B2-46B2-9097-30DD6CAE79A3> I tried running it on Mac and iOS, but it did not work as expected. By the way, we are also trying the following https://developer.apple.com/forums/thread/683624 I have no knowledge of GroupActivity; I have Group Activities set in Capability. Do I need to set anything else? Please let me know if you can find any solution to this message. By the way, I am using Xcode 15.2 Beta, iOS 17.1.1 and iOS 17.3 Beta, Mac OS 14.2.1 (23C71). Best Regards.

I was hoping to add support for SharePlay, but my app is not Universal, because it is around 5 years old. The macOS and iOS versions have different bundle ids, and making a universal app would be a bag of hurt (loss of reviews, migrating data in sandboxed environments and lots more). Am I correct that SharePlay will only work with a single bundle id? I was hoping by simply choosing the same activity type in each app they could connect, but I don't really see how it can given the activity type is hard coded, rather than configured in the Info.plist. If this is the case, it seems like a lost opportunity, not only for "legacy" apps like ours, but also for anyone who might want to work between apps in an app group. Presumably rather than hard coding the activity type, it could have been registered as an Info.plist configuration or entitlement, allowing apps to partake with different bundle ids, the same way it works for iCloud for example.