How to index and deindex NSUserActivities from Spotlight

Question

I am trying to wrap my head around NSUserActivity s and I am not entirely sure on how to use them properly. I have setup my NSUserActivity properly like so:

let attributeSet = CSSearchableItemAttributeSet(itemContentType: kUTTypeItem as String)
attributeSet.title = "Title"
attributeSet.contentDescription = "Description"    

let activity = NSUserActivity(activityType: ActivityType.activity.rawValue)
activity.persistentIdentifier = ActivityIdentifier.activity.rawValue
activity.title = "Title"
activity.requiredUserInfoKeys = ["Key"]
activity.userInfo = ["Key": data]
activity.isEligibleForSearch = true
activity.contentAttributeSet = attributeSet

self.userActivity = activity
self.userActivity!.becomeCurrent()

Now the activity gets indexed via the becomeCurrent() method. When I click on the activity in Spotlight everything works fine and the activity can be restored using the userInfo property.

But how do I delete the activity from Spotlight once it has be used (restored)? In this post the user recommends to use either deleteAllSavedUserActivities(completionHandler:) which works but I can't use since I don't want to delete all activities or deleteSavedUserActivities(withPersistentIdentifiers:completionHandler:) which does not work. For the first method the documentation says following however to the second method this does not apply:

Deletes all user activities stored by Core Spotlight...

Instead I could index the activities with the Core Spotlight API like so:

let item = CSSearchableItem(uniqueIdentifier: ActivityIdentifier.activity.rawValue, domainIdentifier: "DomainID", attributeSet: attributeSet)
CSSearchableIndex.default().indexSearchableItems([item]) { error in
    if error != nil {
        print(error!)
    } else {
        print("successfully indexed item")
    }
}

and delete them with the deleteSearchableItems(withIdentifiers:completionHandler:) method. The problem with that is, I have to set the relatedUniqueIdentifier of my attributeSet and then the userInfo will be empty once I try to restore the activity ( regarding post ).

So what should I do, should I use both Core Spotlight and NSUserActivity and use CSSearchableItemAttributeSet to save the data instead of using the userInfo (why would apple to that?, why would they add the userInfo then?) or should I index my activity without Core Spotlight, but how do I delete the activity from Spotlight in this case?

Answer 1

There is just one thing I figured out: In the apple documentation for the domainIdentifier property of the CSSearchableAttributeSet it sounds like you are supposed to use this property to delete the NSUserActivity

Specify a domain identifier to group items together and to make it easy to delete groups of items from the index. For example, to delete a user activity, you can set this property on the contentAttributeSet property of the NSUserActivity object and then call deleteSearchableItems(withDomainIdentifiers:completionHandler:) on the default().