How to get custom value back from Spotlight with CSCustomAttributeKey

Question

I am trying to get some data back from Core Spotlight which I am storing using a custom attribute key. Tested this on macOS and iOS as well, the result is always the same.

My test class:

import CoreSpotlight

class SpotlightSearch {
  let domainId = "com.company.some"
  let originalDataKeyName: String

  init() {
    self.originalDataKeyName = domainId.replacingOccurrences(of: ".", with: "_") + "_originalData"
  }

  func addToIndex(title: String, content: String) {
    guard let originalDataKey = CSCustomAttributeKey(keyName: originalDataKeyName, searchable: false, searchableByDefault: false, unique: false, multiValued: false)

      else { return }

    let uniqueId = "MyUniqueId" + title
    let originalContent = NSString(string: content)

    let attributeSet = CSSearchableItemAttributeSet(itemContentType: kUTTypeText as String)
    attributeSet.title = title
    attributeSet.setValue(originalContent, forCustomKey: originalDataKey)
    let item = CSSearchableItem(uniqueIdentifier: uniqueId, domainIdentifier: domainId, attributeSet: attributeSet)
    CSSearchableIndex.default().indexSearchableItems([item]) { error in
      if let error = error {
        print("Indexing error: \(error.localizedDescription)")
      } else {
        print("Item '\(title)' successfully indexed!")
      }
    }
  }

  var query: CSSearchQuery?

  func search(title: String) {
    var allItems = [CSSearchableItem]()
    let queryString = "title == '\(title)'cd"
    let attributes = [ "title", originalDataKeyName ]
    let newQuery = CSSearchQuery(queryString: queryString, attributes: attributes)
    newQuery.foundItemsHandler = { (items: [CSSearchableItem]) -> Void in
      allItems.append(contentsOf: items)
    }

    newQuery.completionHandler = { [weak self] (error: Error?) -> Void in
      guard let originalDataKeyName = self?.originalDataKeyName,
            let originalDataKey = CSCustomAttributeKey(keyName: originalDataKeyName)
       else { return }
      print("Search complete")
      for item in allItems {
        let attributeSet = item.attributeSet
        let customData = attributeSet.value(forCustomKey: originalDataKey)
        // Always nil
        if customData == nil {
          print("\(String(describing: originalDataKeyName)) not found in \(attributeSet.description)")
        } else if let originalData = customData as? NSData {
          let data = Data(referencing: originalData)

          if let originalString = String(data: data, encoding: .utf8) {
            print("Found '\(originalString)'")
          }
        }
      }
    }
    query = newQuery
    newQuery.start()
  }
}

On app init:

let newSpotlightSearch = SpotlightSearch()
newSpotlightSearch.addToIndex(title: "Banana", content: "🍌")

Later:

spotlightSearch.search(title: "Banana")

It will find the title, but will not give me back the custom attribute value. If I put a breakpoint after "// Always nil" and use po attributeSet I will get

(lldb) po attributeSet
{
    "_kMDItemBundleID" = "de.axelspringer.SearchMac";
    "_kMDItemDomainIdentifier" = "com.company.some";
    "_kMDItemExpirationDate" = "2018-08-26 00:00:00 +0000";
    "_kMDItemExternalID" = MyUniqueIdBanana;
    "com_company_some_originalData" = "\Ud83c\Udf4c";
    kMDItemTitle = Banana;
}

So the value is there, but Spotlight will not return it to me. Already tried to use NSData instead of NSString for the custom attribute, but same result.

Also found this orphaned question in the Apple developer forums:

CSCustomAttributeKey valueForCustomKey not working

Cave

This may be stupid, but to get it out of the way - what happens if you used the same initializer for CSCustomAttributeKey in search(:) as you do in addToToIndex(::)? So either use the long version ( CSCustomAttributeKey(keyName: originalDataKeyName, searchable: false, searchableByDefault: false, unique: false, multiValued: false) ) or the short one ( CSCustomAttributeKey(keyName: originalDataKeyName) ) in both places, – Footton

It is not stupid, and I already tried it, but the result was the same. – Cave

This is definitely a bug. BTW don't use [weak self] here, otherwise, it will be deallocated if you won't hold the extra reference outside. Self will be in memory until the closure with completion returns which is not a memory leak. – Krystalkrystalle

FYI, for others finding this, this works now. And something easy to forget is to add the key name to the attributes when initializing CSSearchQuery. – Asinine

Answer 1

I believe it's iOS issue. While it's not fixed, maybe Apple will allow you to use a private API to do your thing.

So, attributeSet has private Dictionaries attributes and customAttributes. You can try to get those values using Key Value Coding and ObjC:

NSDictionary *attributes = [attributeSet valueForKey:@"attributes"];
id customData = attributes[originalDataKeyName];

OR

NSDictionary *customAttributes = [attributeSet valueForKey:@"customAttributes"];
id customData = customAttributes[originalDataKeyName];

Key type in those dictionaries is either NSString* or CSCustomAttributeKey*, so you can try supplying both originalDataKeyName and originalDataKey.

Swound

Using private APIs is never an option! – Cave