How to continue an NSUserActivity in SwiftUI

Paul Hudson @twostraws February 9th 2021

Updated for Xcode 13.0 beta 2

New in iOS 14

SwiftUI has a dedicated onContinueUserActivity() modifier that can catch a variety of NSUserActivity types – clicks from the web, launches from Spotlight or Siri, and more. Previously you might have handled this in your AppDelegate using something like application(_:continue:restorationHandler:), but SwiftUI’s approach is more fine-grained and lets us divide functionality more easily.

To implement this, first create a function that will accept an NSUserActivity. You don’t need to do this inside your App struct, but it would make sense to do so because you can then route it wherever you need in the rest of your program.

For example, this function checks to see whether we’re being passed in data from Spotlight, and if so pulls out the unique identifier so you can look it up in your data source:

func handleSpotlight(_ userActivity: NSUserActivity) {
    if let id = userActivity.userInfo?[CSSearchableItemActivityIdentifier] as? String {
        print("Found identifier \(id)")
    }
}

Note: That doesn’t need to check the activityType property, because it will be filtered by SwiftUI in our next code.

Now you can attach that to your main app’s view by modifying your App struct like this:

WindowGroup {
    ContentView()
        .onContinueUserActivity(CSSearchableItemActionType, perform: handleSpotlight)
}

Of course, that’s just the bare bones of handling a user activity – you’ve detected the activity and your code has been run, but now you need to do the actual work of responding to the event somehow.

If you’re not sure where to start, you should probably make your handleSpotlight() set some shared state in your program that drives your UI, for example causing a detail view to present.

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How to continue an NSUserActivity in SwiftUI

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