Firebase Firestore not working in Swift Share Extension

Question

I am building a Share Extension in Swift which saves a document to Firestore. So far I have been able to authenticate the correct user via keychain sharing and app groups. I can also get a documentID from a new document reference:

var ref = Firestore.firestore().collection("stuff").document()
print(ref.documentID) //prints the id

But when I try to save something to Firestore, nothing prints in the console, meaning I get neither a failure or success callback from Firebase (see below where I batch the updates). Here is my ShareController.swift file:

class ShareViewController: SLComposeServiceViewController {

  var sharedIdentifier = "asdf"

    override func viewDidLoad() {
      FirebaseApp.configure()
      setupKeychainSharing()
    }

    func setupKeychainSharing() {

      do {
        try Auth.auth().useUserAccessGroup(sharedIdentifier)
      } catch let error as NSError {

      }
    }

    override func isContentValid() -> Bool {
      return true
    }

    override func didSelectPost() {

      if let content = extensionContext!.inputItems[0] as? NSExtensionItem {
        if let contents = content.attachments {
          for attachment in contents {

            if attachment.hasItemConformingToTypeIdentifier(m4aType) {

              attachment.loadItem(forTypeIdentifier: m4aType, options: nil, completionHandler:  { (results, error) in
                if error == nil {
                  if let url = results as? URL {

                    if let audioData = NSData(contentsOf: url) {
                      let fileName = url.lastPathComponent
                      if Auth.auth().currentUser != nil {

                        guard let myId = Auth.auth().currentUser?.uid else { return }

                         let batch = Firestore.firestore().batch()

                         let ref = Firestore.firestore().collection("projects").document()

                         let project: [String: Any] = [
                           "ownerId": myId,
                           "type" : "audio",
                           "extensionUrl" : audioUrl.absoluteString
                         ]

                         batch.updateData(project, forDocument: ref)

                         let privateRef = Firestore.firestore().collection("user-private").document(myId)
                         let privateUpdate: [String: Any] = [
                           "projects" : FieldValue.arrayUnion([ref.documentID])
                          ]
                          batch.updateData(privateUpdate, forDocument: privateRef)
                          batch.commit(completion: { (error) in
                            if let error = error {
                              print("error updating database: \(error.localizedDescription)")
                            } else {
                              print("Database updated successfully!!!!!")
                              self.extensionContext!.completeRequest( returningItems: [], completionHandler: nil)
                            }
                          })
                        }
                      }
                    }
                  }
                })
              }
            }
          }
       } 
    }
}

Answer 1

It appears you're trying to create additional documents within the projects node and update the user-private node. If so, the code in the question won't work.

UpdateData: Updates fields in the document referred to by document. If document does not exist, the write batch will fail.

Here's a working batch write function that adds a document to a projects node with a Firestore generated document ID and child fields for extension, ownerId and type as well as a user_private collection with a document with a documentId of id_0.

func batchWrite() {
    let batch = self.db.batch()

    let ref = self.db.collection("projects").document()
    let project: [String: Any] = [
        "ownerId": "id_0",
        "type" : "audio",
        "extensionUrl" : "some url"
    ]
    batch.setData(project, forDocument: ref)

    let privateRef = self.db.collection("user-private").document("id_0")
    let privateUpdate: [String: Any] = [
        "projects" : "some projects"
    ]
    batch.setData(privateUpdate, forDocument: privateRef)

    batch.commit(completion: { (error) in
        if let error = error {
            print("error updating database: \(error.localizedDescription)")
        } else {
            print("Database updated successfully!!!!!")
        }
    })
}

Note that self.db is a class var reference to my Firestore. That makes it so you don't have to keep typing Firestore.firestore() and use self.db instead.

Also note that a batch is probably not needed in this case as it doesn't appear there are a significant number of writes occurring at the same time.

If you're not using batch, the .addDocument will add documents to collections.

Here's a function that writes a task to a tasks collection and auto-generates a documentId

func writeTask() {
    let collectionRef = self.db.collection("tasks")
    let data = [
        "task": "some task"]
    var ref: DocumentReference? = nil
    ref = collectionRef.addDocument(data: data, completion: { err in
        if let error = err {
            print(error.localizedDescription)
        }

        print(ref?.documentID)
    })
}

Answer 2

It is likely Firebase wasn't configured for your Share extension. Print statements do not work for share extension. Instead you should make use of NSLog statements i.e NSLog("refDocId:\(ref.DocumentId)"). Then in your xcode, navigate to Window > Devices and Simulators > Open Console. To configure Firebase in your Share extension, use FirebaseApp.configure()